Rosie O'Donnell's Suffering, Strength and Salvation

April 18 -- When Rosie O'Donnell's adoption hotline got a call from a despondent mother saying her 14-year-old girl was raped and impregnated by a youth minister, she felt compelled to help.

The talk show host, who is known for her activism on behalf of children, completely plunged in, deciding to do whatever she could to ease the family's pain. She spent hours on the phone with both the girl and her mother, and even offered to put the girl up in her apartment until she delivered the baby.

Two months later, she found out that both the mother and her daughter were in fact the same woman who suffered from a severe mental disorder. Now, two years later, O'Donnell reveals to ABCNEWS' Diane Sawyer that the little girl she ended up rescuing was actually herself.

An Inconsolable Ache

O'Donnell was 10 years old when her mother died of breast cancer, which she says may partially explain her need to help others.

"I still long for her in moments," she says. "When my son learns another word, when I do an interview with Diane Sawyer and tell the world a secret about me … I want my mom to call me and tell me that I did a good job."

Though O'Donnell was her high school's prom queen, homecoming queen and president of the class, she still felt an inconsolable ache.

"I was an abused kid," she writes. "This is something I've chosen not to dwell on in my public life. It sounds trite, like an ET sound bite. However, sometimes you can't escape a cliché. So yes, I have been abused."

The details, she says, are not relevant or "even really for public consumption. Just know that the effect of that is devastating. It is soul crushing, is almost life-ending for many children … And it takes a very, very, very long way and a very dedicated pursuit in order to put those pieces back together."

She adds, "And there is no person anymore to prosecute."

In her new book, Find Me, O'Donnell reveals that it was her first love — a man — who helped her transform her pain to laughter.