"Life Is Not a Fairy Tale," to air Aug. 19 on Lifetime, is inspired by the R&B singer's autobiography about dropping out of high school and becoming an unwed mother at 17.
"I didn't think it was going to be tough going back playing myself, but it was because I had to relive those moments," Barrino told the Television Critics Association's summer meeting Friday.
"At the end, I began to cry and I said, 'I went through all those things, but I know why I share my life.' I'm thankful that I was able to do it."
A rape scene was particularly unnerving for Barrino, who initially told director Debbie Allen she wouldn't do it.
"She talked to me, and she helped me out a lot," Barrino said. "The good part about it is her son played the part.
"He was so warm and funny. I said, 'If you touch me, I'm going to punch you.' He goes, 'I'm going to punch you back.' So it made it a whole lot easier for me."
Barrino was the third season winner of "Idol" and released her debut album "Free Yourself" in 2004.
"American Idol" airs on FOX, which is owned by the parent company of FOXNews.com.