Kevin Federline heard alarm bells whenever he watched his ex-wife Britney Spears' concerning Instagram videos after the court-ordered termination of her 13-year conservatorship. "With her newfound freedom, I saw history repeating itself," Federline, 47, says in a clip of the audiobook version of his upcoming memoir, You Thought You Knew, exclusively obtained by Us Weekly. "Her social media posts became more erratic. There were the infamous videos of her dancing with knives, cryptic rants and wild behavior that was impossible to ignore.