Amy Schumer’s new book The Girl With the Lower Back Tattoo is sure to be filled with loads of laughs and written in the Trainwreck star’s usual frank and funny fashion. But in the book Schumer also recalls some of her most painful childhood memories, including when she found out her mother was having an affair with her best friend’s father.

Amy SchumerAmy Schumer has opened up about the time her mother confessed to having an affair

At age 13 Schumer says her mother confessed to her that she was having an affair with a married family friend named Lou, who was the father of Amy's best friend. "One day after school I came home and saw my mother slumped on the couch. She'd clearly been crying hard," Schumer writes in an extract published by People.

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As her mother was a teacher of deaf students, she was able to sign to her daughter what she couldn't bring herself to say out loud. "I am leaving your father,” she signed. “Lou and I have fallen in love with each other."

Schumer says that at the time she comforted her mother, something which she now regrets: "I was a child, new to my teens, and she was treating me like a seasoned psychiatrist," she explains.

In the book which is due out next week, Schumer also describes how she lost her virginity to a boyfriend who took advantage of her one night while she was half asleep.

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She writes that it happened: “Without asking first, without kissing me, without so much as looking me in the eyes – or even confirming if I was awake.” The next day her boyfriend apologised and Schumer says she comforted him, telling him everything would be OK. "I was seventeen years old and wanted my boyfriend to like me,” she added.

The Girl With the Lower Back Tattoo hits shelves August 23rd.