According to the source, Britney and her boys made the trip solo - minus even a nanny. "Britney called the concierge desk, saying she was not able to shop herself because she had no one to watch the kids, so would a female please go out and buy her a bright-colored bikini," says the source. "Britney was totally wishing she had help to take care of those kids."

By Wednesday night, the source says, Spears was feeling so overwhelmed by the kids that even though she had planned originally to stay a week she decided to fly back to Los Angeles on Valentine's night. "Something happened," explains the source.

In other news, Justin Timberlake , 26, appeared to take a jab at his ex-girlfriend last night at the Brit Awards when in a taped piece he told the audience, "Stop drinking! You know who you are. I'm speaking to you. You are going to get sloppy." Timberlake then joked, "OK! magazine is going to say something bad about you."

But a rep for Timberlake insists he wasn't referring to the hard-partying Spears, telling Usmagazine.com, "He was addressing the audience at the Brit Awards -- not anyone in particular!"