While Britney Spears remained in rehab, Kevin Federline headed to Las Vegas over the weekend – with the kids.
Federline was in town for a long-planned paid appearance at the Mirage Hotel & Casino lounge Revolution, sources tell PEOPLE.
"Kevin was really low-key," one source says. "You could definitely tell he was on his best behavior. He was having a good time, but wasn't the wild, crazy Kevin who used to come to Vegas."
Federline also plans to return to Las Vegas on March 24 to celebrate his 29th birthday at Pure Nightclub, PEOPLE has learned.
In his latest trip, he arrived on Saturday with Sean Preston, 18 months, and Jayden James, 6 months, plus a nanny, his mother and brother and two bodyguards, sources say.
He had dinner with friends and family at the hotel's Japonais restaurant, says a source, who adds: "He was late for dinner because he wanted to tuck his kids into bed."
By midnight, he was relaxing at a VIP table at the Revolution with a group of friends who included Las Vegas comedian Jeff Beacher.
Spears's rehab ordeal, says a source, has matured Federline.
"He wakes up with a purpose each morning and has enjoyed his family being around him," says the source.
As Britney Spears was reportedly checking out of a drug rehabilitation center for the second time in a week, her estranged husband was making plans to go to court amid a custody dispute over their two children.
Kevin Federline and his lawyer were scheduled to appear at a downtown courthouse Thursday for an emergency hearing, Superior Court spokesman Allan Parachini told The Associated Press.
It was not known what issue Federline planned to raise.
Federline and Spears have two sons, 5-month-old Jayden James and 17-month-old Sean Preston.
Federline filed papers seeking spousal support and sole custody of the children after Spears sought to end their two-year marriage last November.
A temporary court order issued February 1 granted the couple joint custody until the end of this month.
Parachini said Federline's lawyer would try to convince a Superior Court commissioner that the matter is urgent enough to be handled quickly.
