In the new book, You Don't Know, Williams recalls the incident, which she says occurred when she was visiting family friends in California and the family's 18-year-old daughter came into her room one night.
"[She] pulled down the bloomers of my cotton baby-doll pajamas," Williams writes. "'What are you doing?' I asked. 'Don't worry—it'll feel good.' I lay there paralyzed. What was going on? I didn't speak. She kept at [the molestation] for I don't know how long. She slid my bloomers back up and whispered: 'Don't tell anyone.'"
The Emmy-nominated actress, 49, says she kept the secret for years and only began to feel the ramifications of the traumatic event when she was in college. "After that trip I felt something change in me," she writes. "I had always been defiant, but I became a bit more rebellious. I began to pull away from my parents."
But nowadays, Williams says she is much more open about her past, including a photo scandal that cost her the Miss America crown, with her four children. "When my kids have asked about Miss America, those photos or any other part of my life, I told them what I always tell them—the truth," she explains. "After all, it was part of my journey that led me to them and to where I am today."
Williams, who currently stars on Desperate Housewives, is co-starring in the ABC supernatural pilot 666 Park Avenue.