Inside Britney's Breakdown

With Britney Spears on the verge of losing her kids after last night’s mental meltdown, OK! has exclusively learned what happened before the pop star was rushed to the hospital.

“Britney told the court monitor that she didn’t intend to return her children to ex-husband Kevin Federline at the time she was supposed to,” an insider says. “Further, she didn’t intend to return them that night at all!

“The court monitor did her job and decided to terminate the visitation and called the cops on Britney.” Then all hell broke loose — and the star wound up in the hospital mental ward.

Meanwhile, Federline’s attorney, Mark Vincent Kaplan, told OK! he will be appearing at Los Angeles Superior Court at 1:30 p.m. PT to deal with the custody problems. “Kevin will not be there unless it’s absolutely necessary,” Kaplan said. “It’s been a very long night. I’m very tired.”

Kaplan said he’s been to the hospital and was at Britney’s house last night to bring “a document necessary for the identification of the existing court order.”