Article continues below advertisementBritney Spears is firing back after her ex-husband Kevin Federline publicly criticized her mental health.Article continues below advertisementIn a recent interview, Federline claimed he's "terrified" that their sons, Sean Preston and Jayden James, will have to "deal with the unimaginable" because of Britney's alleged "erratic behavior."He added, "I kind of have to sound the alarm that I truly feel that somehow, some way, I just wish that their mom would get help.