Will Kevin Federline tell all about Britney Spears?  Duh, of course he will, he's semi-rich white trash looking for some bank!  K-Fed is prepared to write a steamy, scandal-filled book about his estranged wife that could include shocking details about wild drinking, alleged drug use, her sexual attraction towards other women — as well as her supposed belief in time-travel, according to the new issue of Star.

However, the aspiring rapper may not write the book if he gets what he wants in a divorce settlement from his famous wife.  Sounds like blackmail to me! 

“Kevin is either hoping a publisher will pay him big money for the book,” a source told the tab, “or that Britney will cough up more cash than what’s in their prenup [an estimated $360,000 in spousal support plus $7 million from the sale of their Malibu, Calif., home] to keep him from spilling the beans.”

Federline wants sole custody of their two children as well as a settlement of at least $20 million, reports Star, and is alleging that he can “prove that Britney is an unfit mother” by revealing her partying ways both while she was pregnant and when their babies were born.

As part of his evidence against Spears, Federline is reportedly prepared to use a video he shot — which has appeared on YouTube — in which Spears babbles incoherently.  “Kevin says he filmed it just a week before Brit filed for divorce,” a source told the Star. “He told me, ‘I want the world to see that Britney is an unfit parent and that she’s not in her right mind.’”