According to an insider, Britney Spears had an emotional breakdown when she found out that her sons, Sean Preston and Jayden, have a new babysitter: her soon-to-be-ex-husband Kevin Federline’s BM, Shar Jackson!

With the kids in Kevin’s care since Britney entered rehab for the third time on February 22, “he’s taking control,” an insider says. That includes defying one of Britney’s long-standing demands to keep her sons away from Shar! “It’s really upsetting Britney,” says an insider.