Kevin Federline‘s brother Christopher is making some pretty serious claims…including that he slept with Britney Spears during her marriage to his brother, and fathered her now-7-year-old son Sean Preston!

This isn’t kid stuff, people!

According to the  National Enquirer, Christopher Federline 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. Check out some of this crazy in some clips via Radar.com:

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.”

Yikes.  I’m not saying I trust the Federline family, but geez, these claims seem pretty crazy.  Why would Christopher Federline wait so long to file claims? And, do you think Britney Spears did take part in any of this? I guess I’m asking how much YOU believe of this mess, and how much seems like bogus information…

Photo: FameFlynet

Tags: Britney Spears, brother, jayden james, Kevin Federline, Music, news, paternity, sexual, star