Singer Shania Twain. (Mario Anzuoni/Reuters)

It wasn’t until Lange filed for divorce in 2008 that Twain found out about the alleged affair. “I really lost my sense of trust, compassion, honesty,” Twain said. “Forget that. That’s all dead.” Twain told Oprah that she tried to find out all the details of the alleged affair by writing Thiebaud a heartbreaking letter, which she now calls a “pathetic moment.” Lange and Twain, who, strangely enough, is now married to Thiebaud’s ex-husband, are still in contact because of their son. They have an agreement that Thiebaud is not allowed to see the 9-year-old chid.

Twain said the divorce caused her to “lose her voice,” both figuratively and literally. She has not performed in many years. Now, she’s attempting to get her voice back on her new docu-series, “Why Not?” — debuting this Sunday on Oprah’s OWN network — and through her memoir, “From This Moment On.” When asked if she’ll perform again, Twain said: “I want to. And that’s the whole point of doing it.”

But Twain’s confidence issues began long before her divorce. One clip from “Why Not?” showed Twain visiting her childhood home with her sister. There, she recounted the first time she saw her step-father abusing her mother.

On a lighter note, Twain surprised the entire “Oprah” audience with two-day passes to the 2011 CMA Music Festival in Nashville.

Watch video of Twain’s interview on today’s “Oprah.”