Britney Spears and Kevin Federline have differing viewpoints about his memoir. After Spears, 43, claimed her ex-husband's upcoming book, You Thought You Knew, is a cash grab, Federline, 47, begged to differ in an exclusive interview with Us Weekly on Wednesday, October 15. "Money's not the root of this thing," he insisted. "I feel like, if she has the right to tell her story, why don't I?" Spears issued a fiery statement on Tuesday, October 14, after various publications began releasing excerpts from Federline's tell-all, which hits stores next week.