According to Star magazine, the battle between Britney Spears and her mother, Lynne, is getting more heated by the minute – fueled by what sources claim is Brit’s shocking new accusation that her mom slept with her ex-husband Kevin Federline.

“In a fit of rage, Britney accused her mom of sleeping with Kevin!” a friend tells Star. “Britney doesn’t know up from down right now. She’s so confused and angry, she told Lynne that she was so backstabbing, that she was probably sleeping with Kevin just to hurt her feelings. Lynne, on the other hand, is deeply hurt that her own daughter would so viciously accuse her of doing something so terrible.”

The bitter feud between Britney and her mom, Lynne Spears has been raging for a while. Sources say the singer blames her mother for talking her into entering rehab last February, and the war between them has been getting nastier ever since.

As Star reported, tempers flared on the weekend of June 15, when Lynne made an unscheduled visit to Brit’s mansion. The pair got into a heated argument that sources say turned into a slapfest! “They were swinging at each other,” says an insider.

Days later, Britney confronted 52-year-old Lynne with legal papers warning her to stay away from her grandsons, say sources. And now sources say that in a fit of anger Brit accused her mother of the ultimate betrayal – sleeping with her 29-ear-old ex!

Lynne’s the first to acknowledge that she’s friends with Kevin and goes to his house to see the kids,” says another insider. “But Lynne would never cross that line with him and has zero desire to do so. She goes there because Britney won’t speak to her or let her visit her grand children. She’s given Lynne no other choice.”

Britney and Kevin have just signed a divorce agreement that give them fifty-fifty custody of their sons. But Brit’s out-of-control behavior – from shaving her head in public to threatening photographers in Las Vegas – has been increasingly erratic. And as Star reported last week, insiders say Kevin is “dead set” on getting full custody.

The stress is just adding to Brit’s already fragile state, sources say. “She can’t seem to cope with anything,” the insider reveals. “She cries and says she feels like everyone is against her. I think she’s extremely paranoid. She buys puppies, because they fulfill some desperate need insider her, but the thrill is short-lived, so she goes back and gets another one. She goes out drinking and clubbing because it anesthetizes her and dulls the pain of fighting with her mom and divorcing Kevin. She can’t see it, but the partying is making it worse. Even though Britney’s friends and family aren’t getting along with her right now, they’re really concerned. One day she’s laughing and bouncing with energy and the next day she’s in despair and in tears.”

And friends believe her outrageous allegation about her mother and Kevin is just more proof that Britney isn’t well. “Her apparent paranoia about her mother and Kevin seems to be a product of her current mental state,” the insider says. “All that Lynne and Kevin hope for right now is that Britney will start seeing a therapist to get to the root of her issues, instead of wildly blaming others for her insecurities.”

-Britney Spears music videos