Britney Spears is sharing a piece of her past.

In her upcoming memoir, The Woman in Me, the Grammy winner accuses her ex-boyfriend Justin Timberlake of cheating on her during their relationship, which spanned from the late '90s into the early aughts. According to TMZ, Spears doesn't name the other woman in her book, though the outlet describes the person as "another celebrity."

Spears' memoir will also include details about the singer getting an abortion after conceiving a baby with Timberlake during their relationship, E! News previously learned.

"Justin definitely wasn't happy about the pregnancy," a passage from the book, published by People Oct. 17, alleges. "He said we weren't ready to have a baby in our lives, that we were way too young."

E! News has reached out to reps for Timberlake, who has yet to publicly address Spears' memoir allegations.

Spears, 41, and Timberlake, 42, who first met while working on The Mickey Mouse Club in the early '90s, officially called it quits on their romance in 2002. Later that year, Timberlake dropped his hit song "Cry Me a River," believed to be about the demise of their relationship, along with a music video that featured a Spears look-alike.