Britney Spears Accuses Ex Justin Timberlake of Cheating in Tell-All Memoir

Was Britney Spears "Toxic" or was it her ex-boyfriend Justin Timberlake?

The Princess of Pop has accused the "Mirrors" singer of cheating on her during their early relationship in the early 2000s —more than 20 years after she was claimed to have been unfaithful.

In her upcoming memoir, The Woman in Me, which releases on Tuesday, October 24, Spears alleged that Timberlake cheated on her with another celebrity at some point between when their romance began in 1999 and their 2002 split, according to a news publication.

Spears, 41, opted to not name-drop the star she said Timberlake, 42, was intimate with, as she noted the woman now has a family and didn't think it would be right to involve her name in the resurfaced drama.

The new accusations have prompted fans to re-analyze lyrics from Timberlake's hit 2002 song "Cry Me a River," which the *NSYNC frontman admitted to writing after an intense argument with Spears — who never denied allegations of infidelity against her.

One year later, Spears dropped her iconic song "Everytime," which her writing partner confessed was a direct response to Timberlake's tune.

In the song, Spears sings, "I may have made it rain. Please, forgive me. My weakness caused you pain. And this song's my sorry."

Now many wonder if the lyrics were meant to have a different meaning after a leak of Spears' memoir shockingly revealed she had an abortion after getting pregnant at 19 years old during her relationship with Timberlake.

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Some fans of the "Circus" hitmaker believe her 2003 song could have been about her alleged pregnancy and abortion, especially after realizing a woman gives birth at the end of the music video.

Timberlake — who met Spears when working with her on The Mickey Mouse Club in 1992 — has reportedly been worried about what secrets his ex-girlfriend's memoir would unveil, as OK! previously reported.

"Justin's future is literally in the hands of Britney. She knows everything," a source previously spilled after Spears announced the publishing of her memoir back in July.

"Justin is apologetic and trying to get hold of the manuscript before anyone else does. He has a PR war room set up, but they can't do anything until they read what she has to say," the insider continued.

TMZ spoke to a source about Spears accusing Timberlake of cheating during her memoir.