Troubled Britney Spears is terrified that her husband Kevin Federline will leave her, sources say, now that his ex Shar Jackson has claimed the two are still in love.

Britney and Kevin’s 13-month marriage has been on the rocks, say insiders, since the heartbroken singer went running home to her mom Lynne after a huge spat over her hubby’s party-loving lifestyle.

Kevin then heaped more misery on his wife when she returned home by admitting he enjoyed a night out clubbing in L.A. with his old flame while Britney was at her mom’s, a source says.

Now Shar, who has two children with Kevin, has added salt to the singer’s wounds by revealing she still loves the wannabe rap star — and says he feels the same way!

“I’m gonna love Kevin forever,” Shar told a reporter. When she was asked if Kevin still loved her, she replied: “He doesn’t have a choice. I got in there. You can’t just get rid of that.”

New mom Britney, 24, was probably already fearful of Kevin’s feelings for Shar after she found out he was planning to buy a house for Shar and their kids, Kori, three, and Kaleb, 16 months, close to the $3.4 million Malibu home he shares with Britney.

It is said his confession that he bumped into Shar, 29, at a club while Britney was home with seven-week-old Sean was the last straw.

A close source said: “Britney is in a rage over Kevin seeing Shar while she flew home to Louisiana. She’s absolutely livid that Kevin partied with his old flame while she was out of town.

“Britney is seeing red with Kevin right now. She always seemed very jealous that Kevin’s feelings for Shar still linger on. Britney is also fuming over Kevin spending so much time on his CD project and not with her and Sean.”

Both Britney and Kevin are still together at their Malibu home but friends are worried that could soon change, added the source.

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