Britney Spears claims Justin Timberlake cheated on her in ‘Woman in…

Cry her a river.

Britney Spears reportedly claims Justin Timberlake cheated on her with “another celebrity” during their relationship in her “The Woman in Me” memoir, according to TMZ.

The outlet reported Wednesday that the “Toxic” singer does not name the other woman in her book since the star “now has a family [Spears] doesn’t want to embarrass.”

The former couple dated from 1999 to 2002, with Timberlake’s post-breakup “Cry Me a River” music video leading many to believe that Spears, 41, was unfaithful during their time together.

The *NSYNC member, 42, never directly accused his ex of any indiscretions, and she has yet to speak out — seemingly until now.

Timberlake’s rep has yet to respond to Page Six’s request for comment.

Although the Princess of Pop’s memoir doesn’t hit shelves until Oct. 24, People published excerpts Tuesday about the “Crossroads” star’s decision to shave her head, alleged fat-shaming from dad Jamie Spears, and more.

In addition, Britney revealed she had an abortion while dating Timberlake in late 2000, claiming in candid passages that he “definitely wasn’t happy about the pregnancy” and “didn’t want to be a father.”

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She wrote, “I agreed not to have the baby. I don’t know if that was the right decision. If it had been left up to me alone, I never would have done it.”

Britney, who went on to welcome sons Sean Preston, 18, and Jayden, 17, with Kevin Federline, called the termination of the pregnancy “one of the most agonizing” experiences of her life.

Multiple sources told Page Six earlier this week that the “SexyBack” singer has been “concerned” about Britney’s memoir release.

“He’s very curious what she’ll reveal from their relationship,” one alleged Monday. “It’s eating at him.”

However, a publishing insider insisted that the book was “not a takedown,” but instead a “chance to tell her empowering story and … nothing more than that.”

Timberlake has kept quiet about Britney in recent years, besides encouraging his Twitter followers to “support” her before the dancer’s 13-year conservatorship came to an end.

Since Britney’s bombshell book revelation about him, “The Woman in Me” has shot to No. 1 on Amazon’s bestsellers list ahead of its release.