“I’ve done a lot of living,” the actress says in the current issue of PEOPLE. “I’m a 79-year-old trapped in a 29-year-old’s body.”
Rivera has now chronicled that loaded life in her upcoming memoir Sorry Not Sorry – and PEOPLE has an exclusive excerpt before it hits stores.
The book is full of light and fun memories from an actress who got her start in Hollywood well before kindergarten, but Rivera also does not shy away from serious subjects – including the revelations that she battled anorexia as a teen and had an abortion she got while on Glee – in hopes of letting other women know they are not alone.
“By the time I was a sophomore, I started feeling that what had begun as a game had maybe gone too far. I just avoided food at all costs,” she writes in Sorry Not Sorry of coping with her parents splitting and reuniting at the same time her acting career was stalling. “If my mom had packed a lunch for me, I’d either trash it or find some excuse to give it away.”
Rivera says she didn’t really realize the severity of her eating disorder until she decided to write about it in her memoir.
“I was so young and it just seemed to be the norm. Everyone was going through similar stuff,” she tells PEOPLE. “I had no way of knowing if I was going through it worse. I was juggling my feelings and it makes me sad that there are girls still going through that 15 years after I went through it.”
Harder for Rivera to open up about was the fact she had an abortion.
• For more from Rivera – including the exclusive excerpt from Sorry Not Sorry – pick up the latest issue of PEOPLE, on newsstands Friday
Rivera found out she was pregnant with actor Ryan Dorsey‘s child in late 2010 – just weeks after breaking up with him to focus on her career.
Rivera says she did not reveal the pregnancy to Dorsey, whom she wed in 2014 and is now the father of her 11-month-old son. Instead, she made the call to put her career first and terminated the pregnancy during her one day off from filming an episode of Glee.
“It was very scary to open up about everything,” says Rivera. “It’s not something a lot of people talk about, but I think they should. I know some people might read it and say, ‘What the Hell?’ But I hope someone out there gets something out of it.”
One person she hopes gets something out of her memoir is her son, Josey.
“I hope Josey will read it one day,” she says of the book. “I hope it gives him a better perspective on the issues women face.”
Sorry Not Sorry is on sale Sept. 13.