Oops! She Did It

After years of saying she'd wait until she was married to lose her virginity, Britney Spears is acknowledging that she had sex with her ex-boyfriend, Justin Timberlake.

"I've only slept with one person my whole life," the pop star tells W magazine for its August issue.

"It was two years into my relationship with Justin, and I thought he was the one," she pauses, then adds, "But I was wrong! I didn't think he was gonna go on Barbara Walters and sell me out."

Spears, 21, and Timberlake, the 22-year-old 'N Sync singer, met as kids while performing on TV's The Mickey Mouse Club. They were pop's high-profile power couple for three years before breaking up in spring 2002.

In the video for his song "Cry Me a River," Timberlake gets revenge on a Spears look-alike for a betrayal.

"The most painful thing I've ever experienced was that breakup," Spears says. "We were together so long and I had this vision. You think you're going to spend the rest of your life together. Where I come from, the woman is the homemaker, and that's how I was brought up — you cook for your kids. But now I realize I need my single time."

The singer also discusses her rumored fling with Irish actor Colin Farrell, whom she accompanied to the premiere of his movie "The Recruit" in February.

"Yes, I kissed him. Of course I did! He's the cutest, hottest thing in the world — wooh! He's such a bad boy. But it was nothing serious," she says. "Seriously, I haven't had a boy in a really long time, and I'm really craving ...just a kiss, man. Just a kiss would be nice."