Meg Tilly's star was definitely on the rise. She caught critics' attention for her turn in the 1983 boomer classic The Big Chill and, at age 25, won an Oscar nomination for 1985's Agnes of God. But in 1994, having cooled on the Hollywood lifestyle, she walked away to raise her family. Today the world of premieres and preening, she says, seems "shrouded in mist, like the tail of a dream you can't quite grasp."

There was a time when she felt the same—or tried to—about her childhood. But now Tilly, 46, has decided it's time to lift that particular veil. With the publication of her second book, Gemma, the former actress (whose sister is actress Jennifer Tilly, 47) is speaking publicly about the physical, sexual and emotional abuse she says she endured at the hands of several male relatives and acquaintances—two in particular—throughout her youth.

"You spend the first part of your life—or at least I did—trying to fix things, but you realize that you're constantly choking on your own truth," says Tilly, who lives near Vancouver. "I kept thinking there are other kids out there in these types of [abusive] situations. And I just don't want to carry secrets."

Those secrets date back to Tilly's early years, growing up in California and Canada, a life she recalls of such grim poverty that for food she and her siblings were sometimes forced to catch and cook squirrels and snakes. The third of four children born to Patricia Tilly, a teacher, and Harry Chan, a Chinese-American car salesman, Meg was 3 when her parents divorced. (She then had little contact with her father, who died two years ago.) Her mother soon began dating John Ward, who became Tilly's stepfather and was, she says, a pedophile with a sadistic streak.

She remembers a Christmas when, instead of the usual gifts of candy or whipped cream, she and her sisters awoke to find "the most beautiful dolls we'd ever seen," courtesy of her mother. But the joy soon turned to terror. "We were making too much noise, so [my stepfather] came bursting out of the bedroom and beat us all," she says. "I remember the sound of the belt coming through the loops. He'd whack you across the face. He'd whack you anywhere."

She says Ward also would watch her bathe and was giving her "French kissing lessons" and fondling her by the time she hit early adolescence. "I learned how to get away, how to jump out of my window and climb up the roof," she says.

But Ward, who died a decade ago and was never charged with any abuses, was just the beginning. Tilly's mother officially split with Ward when Tilly was 13 and moved the family in with a boyfriend that Tilly describes as "a monster." "He would all of a sudden pull out the butcher knife and decide you were all going to be killed," she says. (He, too, was never charged.)

Tilly's sister Jennifer declined to comment on the family past. But Tilly's younger sister Becky, 45, an artist, corroborates Meg's accounts. "I share the same memories," says Becky. "Our mother's boyfriend was fiendish. My stepfather was a horrific individual." How does she feel about her sister's openness? "I support her 100 percent."

Tilly doesn't know the whereabouts of her mother's former boyfriend. As for Mom, "I love her very much, but we don't see each other as much as we used to," says Tilly, adding that they only once broached the subject of their past. Tilly gave her a copy of her 1994 book Singing Songs, which Tilly now admits was semiautobiographical. Patricia said, "'Oh, I see what you mean; it's all fiction.'"

Using dancing, then acting skills to escape her dire youth, only then to leave Hollywood behind, Tilly has spent the past decade writing and raising her three children, Emily, 22, and David, 20, from her first marriage to producer Tim Zinnemann, and son Will, 16, from her five-year relationship with actor Colin Firth. She has been married for four years to Don, a writer, whose last name she protects for his privacy. Tilly says that in shedding her secrets, she has never been happier. And she credits her children with giving her the strength to publicly face her past demons. "When you have children, you ask them to tell the truth," she says. "How can you ask that if you don't do it yourself?"