Britney Spears is coming clean.
Two decades after saying she lost her virginity to Justin Timberlake, Spears admits she had sex in high school — years before the former Mouseketeers got together.
The “Gimme More” singer writes in her forthcoming memoir, “The Woman in Me,” that she slept with her brother Bryan Spears’ childhood best friend when she was a freshman and he was a senior, Us Weekly reported Thursday.
She does not name her teenage hookup in the highly anticipated book, which hits stores on Oct. 24.
The confession is a stunning reversal, as Spears, 41, famously declared in 2003 that she had only had sex with “one person [in her] whole life.”
“It was two years into my relationship with Justin. And I thought he was the one. But I was wrong,” she told W magazine at the time.
“I didn’t think he was gonna go on Barbara Walters and sell me out,” the “Crossroads” star added, referring to Timberlake talking about their breakup and sex life on “20/20” the year prior.
The pop stars had a high-profile split in 2002 and subsequently accused each other of cheating.
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In her memoir, Spears confirms long-standing rumors that she “made out” with her choreographer Wade Robson at a bar. She writes that she was otherwise “loyal” to Timberlake, whom she claims stepped out on her multiple times during their three-year romance.
The “Cry Me a River” crooner, 42, has not publicly responded to his ex’s new accusations, though he acknowledged to Walters in 2002 that neither of them was “perfect.”
Spears also reveals in her tell-all that she had an abortion in 2000 but terminated the “surprise” pregnancy because Timberlake “definitely wasn’t happy” and “didn’t want to be a father.”
Ahead of the bombshell excerpts being released, sources told Page Six exclusively that the *NSYNC member had been “concerned” about what the “Toxic” singer would disclose from their time together.
“It’s eating at him,” one insider told us, though another insisted “The Woman in Me” was not intended to be “a takedown.”