Matthew Perry's debut memoir is set to be released next year, and he has promised to be open and honest about his life, problems, and, of course, his time on "Friends" and his co-stars.

His co-stars, in fact, are apparently concerned about what Perry could divulge about them.

Jennifer Aniston, the "Friends" actress with a lot of secrets, is reported to be one of the ones who is particularly concerned.

"Matthew's co-stars are outwardly supportive of his new effort, but there are worries about what he's going to feature on his m," a source told Woman's Day.

"Especially Jennifer Aniston, who people will be wanting to read about the most."

According to the source, the actor from "Fools Rush In" would expose a major secret in his biography.

"It's been rumored that Matthew is being pressured to reveal if [Aniston] truly did hook up with Matt LeBlanc or whether David Schwimmer was interested in her."

According to another claim from New Idea, Perry would reference Aniston's ex-husband Brad Pitt in the novel.

He didn't like Pitt, according to a source, especially after learning of his affair while married to Aniston.

Aside from exposing Jennifer Aniston's relationships and hookups, the Canadian-American comedian will also reportedly talk about his relationship with Matthew LeBlanc.

Though they played best friends on "Friends," they apparently had a totally different relationship when the cameras stopped rolling.

READ ALSO: Kourtney Kardashian Not Inviting Scott Disick To Her Wedding Due to THIS Surprising Reason

The Real Story Behind Matthew Perry's Memoir

Matthew Perry will, in fact, release a "unflinchingly honest" book.

The book is expected to be released in the autumn of next year, according to NME. 

Perry's autobiography will be "candid and self-aware," according to Flatiron Books, a part of Macmillan, and will have "Perry's signature humor" as he "vividly chronicles his lifetime fight with the condition and what fueled it despite apparently having it everything."

However, nothing is known about Matthew Perry's book, but it is safe to assume that it will not reveal the identities of his co-stars because the book is intended to be about him.

It also doesn't appear like he had any issues with LeBlanc, particularly following New Idea's allegation in their story, because they appeared to get along in the "Friends Reunion" special.

Fans will have to wait and see what Perry discusses in his book since they will undoubtedly be intrigued about what it was like to film and work on "Friends."

So it's best to take Woman's Day and New Idea's reports with a grain of salt.

READ MORE: Kylie Jenner, Kris Jenner in 'Crisis Mode' As Makeup Mogul Expected to Lose Millions In Brand Deals -- Here's Why