According to reports, #BritneySpears’ sons allege that the pop star watched them sleep while holding a knife, according to their father #KevinFederline’s new memoir. Federline, 47, details the repeated incidents in his book You Thought You Knew, as excerpted by The New York Times. “They would awaken sometimes at night to find her standing silently in the doorway, watching them sleep - ‘Oh, you’re awake?’ — with a knife in her hand,” Federline reportedly writes. “Then she’d turn around and pad off without explanation.”