Rivera's memoir Sorry Not Sorry is on sale Sept. 13
Credit: Gregg DeGuire/WireImage

In her upcoming memoir

Sorry Not Sorry – excerpted exclusively in the current issue of PEOPLE – Naya Rivera displays her unique wit and sense of humor while sharing her lighthearted memories of early childhood stardom and fun times on Glee, gets real about her past relationships and happy marriage, and opens up about hard times in her life in hopes of helping other young girls and women facing similar situations. Sorry Not Sorry is on sale Sept. 13.

Former Glee star Naya Rivera is no stranger to making headlines, but she took particular offense to the media firestorm that followed her “surprise” wedding to actor Ryan Dorsey in 2014.

“The media eschewed it into this whole thing,” Rivera tells PEOPLE of being accused of simply “switching grooms” when rapper Big Sean called off his engagement to the actress just three months before her wedding to Dorsey.

But, as Rivera chronicles in her upcoming memoir Sorry Not Sorry, she actually had a long romantic history with Dorsey.

“To this day, I’ll be doing interviews and people will be, like, ‘Oh my God! Y’all were friends?’ Rivera says of the media believing her relationship with Dorsey had been solely platonic before their engagement. “I’m, like, ‘What are you talking about?’ ”

The two had dated in 2010 but she ended the relationship to commit herself more fully to her career. A few weeks after the split, Rivera found out she was pregnant with Dorsey’s child. Ultimately, she decided to terminate the pregnancy but never informed Dorsey. The two were not in contact until Dorsey reached out with condolences about her broken engagement.

For more from Rivera – including the exclusive excerpt from Sorry Not Sorry – pick up the latest issue of PEOPLE, on newsstands now

At that point, Rivera began planning an entirely different wedding.

“It was good to tell our story and put the truth out there,” Rivera says of writing her book, which has Dorsey’s stamp of approval. “We’ve been married now two years and have a gorgeous son [, Josey, 11 months,] and it feels good to let everyone know what really happened.”

For more details about Rivera’s love life, career and more, pick up Sorry Not Sorry, on sale Sept. 13.