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Country music star Shania Twain has spoken out about the devastating end of her marriage to producer Mutt Lange, revealing that she opened up about her worst fears to his mistress.

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Unknown to the singer, her best friend and assistant, Marie-Anne Thiebaud, was romancing Lange behind her back.

Opening up about the betrayal in her upcoming TV special, "Why Not?," Twain recalls turning to her pal when she first started suspecting something was wrong.

She says, "She was my confidante, somebody who understood.

I said, 'Marie-Anne, don't you think that my husband is acting strange?' and she said, 'No, I don't see anything strange... He's fine.' All Marie-Anne did through the whole thing was comfort me, telling me, 'Everything's fine' - and I believed her and I accepted it as being genuine."

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Thiebaud's husband, Frederic, who became Twain's spouse on New Year's Day, admits he uncovered the affair shortly after Lange filed for divorce from the singer - and decided to tell the star that her husband had been cheating on her with his wife.

He says, "I had to tell her... She was really heartbroken."

Twain recalls, "It really hurt. First I found out my marriage was over and then the next day I found out about the affair. My own friend, who I had confided in. I still can't get my head around that."

Appearing on "The Oprah Winfrey Show" on Tuesday, Twain revealed she wanted to kill herself as the drama unfolded: "I just wanted to go to bed and never get up."

And in her new memoir, "From This Moment On," Twain recounts that the heartbreak left her with the shivers.

Reading from the book on "Oprah," she said, "I was freezing cold all the time, and my only relief came when I'd strip off my clothes and climb into a steaming-hot bath ... five times a day. ... I'd be shivering most of the time, shaking uncontrollably. ... I couldn't get rid of the chills."

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