Kevin Federline was not a #FreeBritney supporter. In his upcoming memoir, You Thought You Knew, Federline, 47, writes that the fan-led movement to end his ex-wife Britney Spears' 13-year conservatorship may have "started from a good place," but he believes it ultimately did more harm than good. "All those people who put so much effort into that should now put the same energy into the Save Britney movement," he writes in an excerpt published by The New York Times on Tuesday, October 14. "Because this is no longer about freedom. It's about survival." Federline says Spears' supporters "vilified" her estranged father and former guardian, Jamie Spears, after the pop star, 43, described her conservatorship as "abusive" in court in 2021, just months before a Los Angeles judge terminated the legal arrangement. Britney Spears and Kevin Federline's Timeline: From Divorce to Coparenting As a result, Federline worries that the people around Britney nowadays cannot step in without getting backlash like her dad, 73, did when he controlled her personal, medical and financial affairs. "The truth is, this situation with Britney feels like it's racing toward something irreversible," Federline writes of Britney's recent erratic behavior on social media. "It's become impossible to pretend everything's OK. From where I sit, the clock is ticking, and we're getting close to the eleventh hour. Something bad is going to happen if things don't change, and my biggest fear is that our sons will be left holding the pieces." Kevin Federline Listenin Britney and Federline were married from 2004 to 2007 and share two children: Sean Preston, 20, and Jayden James, 19. Less than a year after the exes finalized their divorce, Jamie placed his daughter under a conservatorship in response to a public breakdown she had suffered. Inside Britney Spears' Life Today: The Truth About Her Finances, Boyfriend Now that Britney is free to make her own decisions again, Federline is calling on anyone "who has ever been moved by" the "Toxic" singer to stand by their sons, though he admits he does not know the perfect "solution" to her struggles. "More than ever, they need your support," he writes in the book, per the Times. "I've been their buffer for years, but now it's bigger than me. It's time to sound the alarm." In an interview, Federline told the newspaper that he has not spoken to Britney "in years," as their kids are now legal adults, but he insisted he always will be in her corner. Britney Spears' Ups and Downs Over the Years "I've never, ever, once, been against Britney," he said. "I've only tried to help my sons have an incredible relationship with their mother. And it's hard because when I really reflect on everything that's happened - my kids do not know the woman that I married. And I've spent two decades trying to bridge that gap." In response to Federline's claims, Britney's rep says in a statement to Us, "With news from Kevin's book breaking, once again he and others are profiting off her, and sadly it comes after child support has ended with Kevin." Her rep continues, "All she cares about are her kids, Sean Preston and Jayden James, and their well-being during this sensationalism. She detailed her journey in her memoir [2023's The Woman in Me]." You Thought You Knew is available in bookstores next Tuesday, October 21.