Funnywoman Amy Schumer once feared for her life at the hands of a violent ex.

The Trainwreck star, 35, recalls the scary encounter in her new book The Girl With the Lower Back Tattoo.

"He grabbed a huge butcher knife from a drawer. And that’s when I was sure he was going to kill me," Amy wrote, according to a book extract obtained by People magazine.

She uses the experience to warn fellow females to watch out for violent men, adding, "It can happen to anyone. You’re not alone if it’s happening to you, and you’re not exempt if it hasn’t happened to you yet."

The comedienne also opens up about he relationship with her mother, Sandra, who had an affair with a family friend when she was 13.

In the book she reveals she used to idolize her mom but they have had a tense relationship for years, ever since Sandra owned up to her illicit romance with the father of Amy's best friend.

"We love each other and I'm really grateful to her and for her, but we'll never be how we were," she told USA Today. "I wrote that family is a constant negotiation so it's constantly evolving, but we'll never be close again."

In the memoir, which was released on Tuesday (16Aug16), Amy also goes into detail about her father's battle with multiple sclerosis and recalls her first sexual encounter.