The birthday party kicked off Saturday night, Social House.

"He was talking on the phone and texting the whole time," said the source.

Later, Federline made his way to Caesars' Pure Nightclub.

"As soon as his parents got to the club they immediately went to Shar's table on the other side of the club and hung out there for a while," a source says. "They were taking photos with her and catching up. It's pretty easy to see that they still care about her."

Federline "was clearly having a good time, hanging with his group and singing along to most of the music," says an onlooker.

At 2:30 a.m., Jackson again returned to Federline's table to dance with his parents. Federline then grabbed the mic, says a source, and said to the crowd: "'My entire family came out for my birthday. My brothers are here, my mother, my father, my sister and even my ex Shar Jackson came out for this.'"

Meanwhile, Britney Spears' and Kevin Federline's divorce has reportedly been finalized, but the details of Kevin's payout are still unclear.

Britney Spears reportedly left the Promises rehab center before officially checking out so that she could finalize her divorce from Kevin Federline.

Reports claim that Federline will receive $19 million, a $2 million lump sum, half of Britney's earnings during their marriage, and half of the earnings from the sale of their Malibu home.

TMZ claims that Kevin Federline is not getting anywhere near the reported $19 million divorce settlement.