May 5, 2011 -- Although her songs exude passionate love, country-pop singer Shania Twain knows what it means to be heartbroken.
In an interview with "Nightline" anchor Cynthia McFadden, the famously private performer opened up about growing up hungry and poor in an abusive household, her husband's reputed affair that ended their marriage and her finding love again.
Twain, 45, who has never exposed her personal life in such a public way before, said she now wanted to "testify" to her experiences to help others. Her new memoir, "From This Moment On," is in stores now.
"I think I've remained very detached from my life to this point, almost as though it was a different person, every phrase I went through," Twain said. "So I've reconnected and said, no, this is actually who I am. I'm neither embarrassed of who I am, where I come from, what I've experienced, I'm not ashamed of it."
Growing up in the small town of Timmins, Ontario, Canada, Twain told McFadden about the years of physical abuse she said her mother Sharon endured from her stepfather Jerry Twain, the man she always called "Dad."
"[It was] overwhelming for any child to never know what to expect from one day to the next," Twain said. "It could happen anytime. But also you don't know if they're going to survive it."
Jerry Twain legally adopted Shania when she was 4. She recalled his abusing her and her mother consistently throughout her childhood, including one terrifying incident in which she watched Jerry plunge Sharon's head into the toilet.
"I thought he'd killed her," Twain said. "I really thought she was drowned, or dead, or that he had just smashed her head in and she was never going to wake up. ... She looked dead. She was unconscious, she was limp, hanging from his, you know, her, he had her hair in his hands.
"So I'd gone though the shock and experience of really believing my mother had died at that moment," she continued. "Also, through the humiliation of how I thought she had been killed, by drowning in a toilet seat. ... It was very, very obviously very hard to take."
But she said the abuse didn't stop with her mother. To this day, she said she doesn't understand why her father, a man who had taught her to be a good person, was so verbally abusive toward her.
"It was the Jekyll and Hyde in him that was the greatest torture," she said. "I loved him and I respected so much what he did for us, being the hard worker, he set a great example. So I'm still left confused. I'm baffled by all of that, I really am."
Burdened as her parents were with five kids, Twain said their arguments stemmed from their financial struggles. There often wasn't enough money to pay the rent or buy groceries, Twain said, so she repeatedly went to school hungry.
"It's very hard to concentrate when you're stomach's rumbling," she said.
Twain said that she remembered getting jealous of the other kids' lunches but never told anyone.
"I would certainly never have humiliated myself enough to reach out and ask for help and say, You know, I'm hungry. Can I have that apple that you're not going to eat?" she said. "I didn't have the courage to do that."
Twain's challenges continued when her parents were later killed in a car accident in 1987, leaving her to raise her three younger siblings.
Shania Twain Says She Developed Dysphonia After Ex-Husband's Alleged Affair
Twain's breakout album, "Come On Over," released in 1997, was a joint project with music producer Robert "Mutt" Lange, 62. The couple produced many songs together in the years to come and eventually fell in love and married. For Twain, it was practically love at first sight.
"When I met Mutt for the first time, I knew that I loved this person." Twain said. "I felt like I had already loved him."
But with her punishing tour and studio schedules, Twain said she eventually began to sense that something was wrong with her marriage around the time of her 2004 "Up" tour.
"When I started to get lonely, then I knew that something wasn't right," she said. "I'm married to someone I love, and I'm so lonely...I didn't want to live that way."
Twain said she began confiding heavily in her close friend, Marie-Anne Thiebaud. They were friends for years until Twain confronted Thiebaud and Lange about having an affair, which she said would ultimately end Twain and Lange's 14-year marriage. She divorced Lange in 2009. Both Lange and Thiebaud have publicly denied the affair ever happened.
"Whether she was part of the cause ... of the breakup or whether it was just me leaning on her because it was already breaking up, I really don't know which came first," Twain said. "What I do know is she took advantage of, you know, the weakness in the relationship between Mutt and I."
Twain hasn't spoken to Thiebaud in person since confronting her about the alleged affair. Her ex-husband repeatedly denied it for months after she confronted him, Twain said, and he left a lot of "open wounds" for her.
"I was angry at Mutt for not listening to me and not answering my questions, more than the affair itself," she said.
Since learning of Lange's alleged betrayal, the five-time Grammy winner said she has developed dysphonia, a physical and physiological ailment that doesn't allow her to sing properly.
"The muscles literally constrict the voice box and prevent air from flowing properly," Twain said. "You don't get any volume, which is not very good for a singer."
"It's got nothing to do with the vocal chords, the voice is perfectly fine," she continued. "I would say the envelope around the vocal chords is restricting, and not allowing the vocal chords to do their job."
Without a powerful singing voice, Twain has slowly reinvented a new way to make her voice heard, in part through her memoir, "From This Moment On," and also through a new reality series on the Oprah Winfrey Network called "Why Not? With Shania Twain," which premieres May 8.
"I spent a lot of my life holding back my cries, and I want to change that because it's not good for me," Twain said. "So the journey through the 'Why Not' series is part of that, writing the book is part of that."
"Talking about it now is all part of that, forcing myself to do things that are difficult," she continued. "Take myself out of my comfort zone, face my anxieties and just get more comfortable with my fears."
After going through a vicious public divorce, Twain eventually found love again in a familiar face: Frederic Thiebaud, Marie-Anne's ex-husband. The couple married on New Year's Day 2011.
"I fell in love, I can't believe it because I didn't ever want to know love again," she said. "I've always believed in love. I temporarily lost my hope in love, and it was temporary thank goodness."
Even as someone who wrote some of the most treasured love songs and then went through incredible heartbreak with the same man, Twain said she will always cherish the songs she and Lange produced together.
"I still think they're beautiful," she said. "Nothing of my present or my future will ever take away what I had in the past, ever. I would never disrespect myself and do that. I'm very happy with every love song I ever wrote in my marriage to Mutt, and I'm very proud of the work we did together."