Kevin Federline's Brother: "I'm the real father of Britney's baby!"

Baby, if this don't sound like some, "I want to be famous... type my name on the internets and pay me $5,000 so I can catch up the payments on my trailer" type mess right here - I don't know what.

But, if this were true... wouldn't this be a "gatcha!" for Kevin Federline, who was engaged to Shar Jackson when he started dancing for Britney and left her pregnant when he realized that he could snag a real star?

According to Radaronline:

Kevin Federline's brother Christopher says in bombshell court papers that he slept with Britney Spears during her marriage to his brother - and fathered her now-7-year-old son Sean Preston - and RadarOnline.com has the details.

Christopher Federline, as first reported by the National Enquirer, filed for a temporary restraining order against Britney on December 18 in U.S. District Court in Tampa, Florida, claiming The X Factor judge has stolen from, blackmailed and harassed him.

"She is out-of-control and a maniac," he said in the court docs.

In the papers, Christopher says Britney recently "went to Kevin's house to pick up Sean Preston and Jayden James, and [his] wallet was on Kevin's coffee table when Britney opened it up and stole [his] Capital One credit card."

Christopher claimed in court docs that when he followed up on the alleged theft - which accounted to more than $4,500 in charges - "Britney … laughed at me [and] told me my brother Kevin ruined her life. Britney made fun of me and told me I have a small penis.

"She also blackmailed me and told me if I tell the police that she stole my credit card, that she will tell the world I’m the true father of Sean Preston, not Kevin.

"I do confess I slept with Britney, and I am the true father, but the public does not need to know," he admitted.

A source told the Enquirer that when Christopher contacted Britney about the credit card, she "just laughed at him," and "threatened to tell Kevin she and Chris had sex while she was married to Kevin ... and tell everyone that."

An insider says that "Chris says the fling was a mistake. He says he always felt bad about it and kept it to himself because he didn't want Alisha, his wife at the time, to find out."