Britney Spears vhecked out of rehab after less than 24 hours – then checked back in days later. The reason for the quick turnaround? An ultimatum from Kevin Federline, a source tells PEOPLE.
Upset by the news that Spears had checked out of Promises in Malibu on Wednesday, Federline scheduled an emergency hearing to seek physical and legal custody of their sons Sean Preston, 18 months, and Jayden James, 6 months, says a source.
Federline, 28, gave his estranged wife a choice: Either she got back into Promises that night or Federline would go to court in the morning, says the source.
"Kevin is working closely with Lynne to let Britney know how serious it is that she gets help," says one family friend. A source close to Federline notes that "Kevin loves Britney ... nothing has changed about that."
Right now the boys are "being taken care of by Kevin," and"Lynne is helping."
Kevin, who will turn 29 this month, "would like [Britney] to have the kids because he thinks she is a good mother."
But to make that happen will require hard work. A typical stay at Promises lasts 45 days – and Spears "is getting no special treatment," says her manager Larry Rudolph. "She has a regular room, a regular routine. She is doing exceptionally well."