Kevin Federline's Wild B'day Bash

Kevin Federline spent his birthday with an ex-but not Britney Spears. Federline's Saturday night birthday festivities in Las Vegas included none other than ex-girlfriend Shar Jackson.

Federline arrived in Las Vegas on Friday afternoon to celebrate his 29th birthday, which was March 21. He brought along his sons, Sean Preston, 1, and Jayden James, 6 months, while mom, Britney Spears, remained in Los Angeles. Federline checked into Caesars Palace and hung out in a VIP cabana at Caesars' Venus Pool Club, according to People magazine.

The partying began Saturday night at Social House where Federline ate Asian food with 14 family members and friends. "He was talking on the phone and texting the whole time," a source told People.

The night continued at Caesars' Pure Nightclub, where Federline's ex, Shar Jackson, was already waiting.

"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 drank the night away, hung out in his VIP area, and waved to yelling fans. At 2:30 a.m., Shar Jackson returned to Federline's table to dance with his parents. Federline then grabbed the mic 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."

Britney Spears was MIA, but then again, she did just get out of rehab.