tonight on "nightline," full circle. president obama and the families of 9/11 victims -- >> i don't wish anybody to have to walk this journey. >> make an emotional journey back to ground see ree. we have a very personal story of a very private meeting. with bin laden dead, can these families find peace? plus, shania speaks. she's the country star who set pop music on fire. that nigh what twain speaks out about marrying the ex-husband of the woman she says broke apart her marriage. and how she's still trying to get her singing voice back. and, canine commandos. how to fight terrorists? with counter-terriers, of

course. we'll show you how the dogs of war, like the one that helped nab bin laden, get ready for battle. >> announcer: from the global resources of abc news, with terry moran, cynthia mcfadden and bill weir in new york city, this is "nightline," may 5th, 2011. >> good evening. today, chilling information gleaned from osama bin laden's compound. material con his kated from there revealing al qaeda was planning a possible attack on the united states four months from now, on the tenth anniversary of september 11th. it's still unclear how viable the plan was, but we know the target was passenger trains. meanwhile, president obama traveled today to ground zero to honor the fallen and meet with some of the victims' families. we began the day with one of them. >> he skied in colorado. >> reporter: rose mary cane's

son's name was george. he was 35 when he was killed on 9/11. he was a firefighter stationed in midtown manhattan. on that day, one of hundreds of first responders who rushed into the towers after they were hit. remember walking in my house and turning on the television and, you know, those crueller cn the bottom of the screen. and i remember seeing "hundreds of firefighters trapped." i'll see that until the day i die. >> reporter: she's made the drive to ground zero so many times since then. >> it's a funny thing about september 11th. some people say, they knew right away. they knew right away. they had no hope. i didn't really feel that way. george being the kind of guy he was, that i just thought to myself, okay, if anybody can get

themselves out of there, george can get himself out of there. >> reporter: hope eventually died. and osama bin laden? >> i wanted them to blow him off the face of the earth. >> reporter: and so today, rose mary cane, a life long republican, is doing this drive again. this time, because she's been invited to meet with president barack obama. when did you find out that osama bin laden had been killed? >> actually one of the other mothers called me, and i was sound asleep, and she woke me up and said that they had gotten bin laden and that he was dead. and i got kind of emotional, i didn't know if i should cry or whatever. i was ready to go lay down and go back to sleep and then the phone never stopped ringing after that. >> reporter: president obama arrived in new york city and headed straight to a fire house, engine 54, battalion 9. 15 firefighters died at this house on 9/11. he talked to the men and their

families gathered there. >> what happened on sunday, because of the courage of our military and the outstanding work obvious our intelligence, sent a message around the world but also sent a message here back home that, when we say we will never forget, we mean what we say. >> reporter: just about the same time, rose mary cane was heading to another fire house, ladder 7 on 29th street. >> how are you? >> where my son was. his fire house. and i always have to go there. the big happy smiling guy up there. that's my george. this was the fire house he loved. he was here for seven years. and these are the brothers that -- they all went to heaven together on 9/11. >> reporter: down at ground zero, president obama laid a wreath at the memorial plaza, still under construction. then, had a very private meeting with survivors families.

rose mary was to be one of them. the media was not allowed inside. but we have a few pictures of that meeting. >> the president came in, and everybody was really excited to see him. and he was very nice, very cordial to everybody. and then he started coming around and speaking with everybody. >> reporter: the president also met with patricia riley, whose sister died on the 101st floor of the south tower, the second tower to be hit. >> today represents for me, a closure for the justice my sister deserved. i was so grateful that the last thing osama bin laden saw was an american soldier who came to get him for what he had done to us. >> i mean, closure, how can you have closure when you don't have a human bone? >> reporter: bill doyle's son died on the 101st floor, too. what did it mean to meet the president?

>> i was ecstatic. it's amazing how compassionate that man is. he really has a heart. >> reporter: jim richards also met with the president today. he lost his firefighter son. as did they all. >> this is like a club that we didn't want to join, but we're in it. and somebody said the other night, like, we met the nicest people, but it was the worst way you want to meet them. we all lost a son, a daughter, a loved one. and you make good friends with this, but it's very difficult, and we all struggle each day and i think obama by hugging us, he was a father who told us, i have two daughters and i can't man how you would feel. >> reporter: how was their meeting with the president? what did you say to the president? >> i thanked him for having the courage to allow our military to do the job that needed to be done. >> people were able to identify with him. it was an honor for me. >> reporter: for rose mary, like the other families we talked to, the killing of bin laden

provided a sense of justice. but not closure. it will never bring their loved ones back. >> when i see the firefighters, i always get a big hug. i love to go to the fire house, and i get a big hug from them all. and i just -- i close my eyes for just a second and i make believe it's george. so -- he owes me a lot of hugs. >> there are still more than 1,0009/11 victims whose remains have never been identified. rose mary also told me she asked the president to do everything he could to ensure they were treated with the respect they deserve. just ahead, we'll shift gears to the world of entertainment, and the woman who famously sang "you're still the one." but shania twain now says the man she wrote the song with betrayed her.

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>> announcer: "nightline" continues from new york city with cynthia mcfadden. >> well, she was the first country star to achieve major crossover success in the world of pop music. five-time grammy award winner shania twain's 1997 album "come on over" is the best selling album of all-time by a female musician. she sold more than 75 million albums world wide, but she hasn't released an album of new material since 2002, and in the last several years, she seemed to retreat from public life entirely. until now. ♪ man i feel like a woman >> reporter: we know her music. through hits such as "man i feel

like a woman." but until now, we've known little about her. a lot of people who have gone through what you've gone through would be hiding in a closet somewhere. >> what does that mean? >> reporter: i mean, it's a lot. >> i think i remained very detached from my life to this point. almost as though it was a different person every phase i went through. and i i've reconnected and said, no, this is actually who i am. i really want to help people with my testimony. >> reporter: and testify, she does. in her new book, "from this moment on" and documentary series, "why not with shania twain." she lays bear her life, starting with her childhood. >> this was the bedroom for the four of us. just from me to the stairs. >> reporter: where she often went to school hungry. it's not just that you were hungry, but you were embarrassed. >> right, so i never talked about it. i wouldn't admit it. i would lie why i didn't have a

lunch. i wanted to protect my parents, first of all. i didn't want them to get expos exposed. >> reporter: it was the beginning of a pattern of hiding the painful things in her life. her mother, being routinely beaten by her father. and her father verbally abusing her. what would he say to you? >> well, i wouldn't be able to say the words on television. >> reporter: he used the c-word in reference to you? >> all of those really, really terrible words. the worst ones you can imagine. it was almost a psychological game of torture. >> reporter: do you forgive him? >> completely. because i lived it with them. when i was hungry, they were hungry. in fact, if anything, i sense now that i'm a patient i sense more the burden they must have gone through. >> reporter: perhaps forgiveness comes from losing them so early. they died in a car accident when she was only 22. for the next six years she did whatever she could to support her siblings and keep her music alive. ninely, in 1995, "any man of

mine" hit number one. ♪ any man of mine >> reporter: her collaborator and husband, the legendary producer mutt lang, helped make it happen. >> when i met mutt, i knew that i loved this person and felt like i had already loved him. >> reporter: you made a lot of great music together. >> we made a lot of great music. ♪ from this moment on >> reporter: "from this moment on," just one of them. the couple eventually moved to switzerland to be out of the spotlight and had a son named asia. she found a best friend, mary a an ann. >> there was no other girlfriend at the time. >> reporter: she says things were not going well in her marriage. >> and all the while i'm confiding in mary ann. it just dawned on me to ask, do you think it's possible he might be having an affair, and she says, of course not. >> reporter: but twain says, he

was. and mary ann's husband broke the news to her. >> fred called me and said, i don't know if you want to know, but i -- there's something i think you need to know. about mutt and mary ann. >> reporter: did you believe him? >> no. i didn't. i didn't believe him. >> reporter: did you confront mutt? >> of course i did. i confronted mutt and mary ann. >> reporter: who first? >> she changed her phone number very quickly. she came over for dinner one night and i said, you know, are you sure there's nothing you want to share with me, something you're maybe holding back? and she said no, of course not. and she started crying a little bit. about how disappointed she was in me, that i mistrusted her. i said, fred, i'm telling you, you're wrong. she is innocent. and then i said good-bye to mary ann. i never did see her again. >> reporter: so, when you finally get arnold to talking to

your husband, how does that go? >> he denied it. for a very long time. probably even more than a year. >> reporter: it sounded like you were more angry with her than with him. >> yes. >> reporter: why? >> for interfering with something so dear to me. it was just the most disrespectful thing to do. to interfere with a marriage that's weak. and i just found that extremely unfair. >> reporter: we were unable to reach mutt or mary ann for a comment. but they have both previously denied having an affair. nevertheless, twain says she was devastated and could barely get out of bed. >> when i found out, i went right into shock. the person to comfort me was fred. i should have got the role for that. because he's been through the same thing. >> i fell in love with her. >> that's when i said, whoa, i'm not falling in love.

i don't want love. >> reporter: the final twist in all of this, which is almost unbelievable, is that you fall in love with fred. >> uh-huh. i fall in love again, never mind with who, even, again, i'm -- i fell in love, i can't believe it. >> reporter: you're a newly wed. look at that. just jan first, right? >> that's right, jan first. >> reporter: while she's raising her voice to tell her story, she is struggling to reclaim her singing voice. >> it physically will not come out of my throat. the aspect of it, there's nothing wrong with my actual voice. it's the envelope around the vocal chords that is restricting. >> reporter: listen, i'm no doctor, but i read the book and i say to myself, is it a quince dense that her husband and best friend betray her and she's not feeling like she can really sing out and it feels a lot like when

you're holding back a cry, you say? >> yes. i spent a lot of my life holding back my cries. i want to change that. >> reporter: can you make an album without mutt? >> yes, of course i can. can i make a great album without mutt, i don't know. >> reporter: but what of all the great love songs they did make? like "you're still the one." but she still leave in that? >> i temporarily lost my hope in love. and it was temporary, thank goodness. and i believe very much in love. ♪ you're still the one >> we can't wait to hear her sing again. her book is in stores and the documentary series starts on the oprah winfrey network on sunday. next up, these dogs do a lot more than fetch. they help nab terrorists, including osama bin laden. we look at how dogs suit up to go to war.

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well, they're part of the elite navy s.e.a.l. commando team that swept into pakistan and killed osama bin laden. they are trained to attack,

trained to kill, all 3,000 of them, fierce warriors on four legs. take a look at these incredible pictures. this is our favorite. a parajumping pup. unlikely member of the united states special forces. some jump out of military aircraft. choppers. into war zones. side by side with their human comrades. trained alongside them to be the best of the best. the dogs are equipped from nose to tail with top military gear. such as waterproof body armor, resistant to bullets and knife attack. head mounted infrared live cameras. and ear bugs. their jaws pack 400 to 700 pounds of pressure. the military uses a variety of breeds, the most common are the german shepherd. brave dogs. go get them, fido. that's our report for tonight. we hope you watch "good morning america" tomorrow.