Britney Spears accuses Justin Timberlake of cheating with a fellow celebrity

The singer dropped the bombshell allegation that her famous ex had an affair with another celebrity during their high-profile romance.

Justin Timberlake and Britney Spears.

Britney Spears has reportedly accused Justin Timberlake of cheating on her with another celebrity during their three-year relationship.

According to TMZ, the Toxic singer, 41, makes the explosive allegation in her upcoming memoir, The Woman In Me, which will be released next week.

Timberlake and Spears were one of the most high-profile couples in Hollywood when they dated between 1999 and 2002, after first meeting as young kids on The Mickey Mouse Club TV series in 1992.

Who could forget the double denim date? Picture: Jeffrey Mayer/WireImage

They were together from 1999-20002. Picture: Lucy Nicholson/AFP

Just months after Spears confirmed their split, Timberlake released the break-up anthem, Cry Me A River – featuring a lookalike of his famous ex in the music video – leading to plenty of speculation that she had cheated on him.

(It’s not hard to see why, with the lyrics including: “You don’t have to say what you did/ I already know/ I found out from him.”)

Spears now claims Timberlake cheated on her.

More than 20 years later, Spears is reportedly finally sharing her side of the story – which paints the former NSYNC star in a very different light.

However, TMZ reports that Spears refuses to name the female celebrity involved in their love triangle, as she now has a family she doesn’t want to embarrass.

It’s not the only bombshell detail about the singers’ former romance that is shared in Spears’ highly-anticipated memoir.

People magazine published an excerpt on Wednesday, which also revealed for the first time that Spears had fallen pregnant with Timberlake’s child when they were in their late teens, but had gotten an abortion at his urging.

“It was a surprise, but for me, it wasn’t a tragedy. I loved Justin so much. I always expected us to have a family together one day,” she wrote, according to People.

“This would just be much earlier than I’d anticipated. But Justin definitely wasn’t happy about the pregnancy.

“He said we weren’t ready to have a baby in our lives, that we were way too young. I’m sure people will hate me for this, but 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. And yet Justin was so sure that he didn’t want to be a father.”

The Overprotected star added that it was “one of the most agonising things I have ever experienced in my life”.

The Woman In Me will be released on October 24.

Originally published as Britney Spears accuses Justin Timberlake of cheating with a fellow celebrity