February 1, 2007 -- KEVIN Federline may be done with Britney Spears, but he's not done with the friends he collected during his short-lived marriage. Sources said that while Britney's brother Brian Spears was in L.A., Fed-ex partied with his buddies, including Brian's roommate, at downtown lounge Butter on Monday night. "He is still really good friends with Brian's roommate," said our spy - although Federline and Co. opted to head back to the hotel instead of his ex-brother-in-law's pad. "Brian isn't the biggest fan of Kevin," said our source. Federline's rep, Marilyn Lopez, confirmed the story.