Article continues below advertisementBritney Spears has been pushed to breaking point by a renewed and deeply personal conflict with ex-husband Kevin Federline, sources have told OK!, with the escalating row over their sons preceding the singer's DUI arrest in California.Spears, 44, was recently taken into custody in Ventura after being pulled over while allegedly driving erratically in a BMW convertible, with officers reporting swerving, braking issues and no tail lights. She spent nine hours in custody after being booked at the Ventura County Sheriff's Office at around 3 a.m.