It's for real: Britney Spears, 22, married dancer Kevin Federline, 26, on Sept. 18 in a Studio City, Calif., ceremony that took even her parents by surprise. "That was one of the first things she said to me: 'Mama, I kept a secret!' " recalls mom Lynne Spears. The couple have 90 days to file their marriage license. "Basically, those reports that we didn't legally wed are b-------," Federline told PEOPLE. "But it doesn't bother me."