Star Magazine is sticking by the story, featured in last week’s issue of the gossip rag, that former “Good Burger” star Shar Jackson and Britney Spears’ faux rapper on-again/off-again ex are expecting another little Federfreak.

“When Kevin heard about the story in Star today, he called up Shar and asked her if she was pregnant and she told him ‘yes.’” moles dish. “Kevin asked Shar to deny that she’s pregnant….at least for now, until they’ve both had time to figure out what to do.”

It turns out that while Britney Spears was busy getting her act together at Malibu’s Promises rehab facility, Federline — the father of her two children — was busy getting it on with his other baby mama, Shar. And even more shocking, they were doing it without using any protection!

A Shar source reports: “Shar told me, ‘I’m pregnant, I just know it. I know when I have a baby inside of me!’” The mother of four (two with Kevin and two from a previous relationship) said she was about three weeks gone, because that was the last time she made love with Kevin, and she hadn’t slept with anyone since!”

According to another insider: “Britney’s going to freak — she’ll see this as a slap in the face!”