Britney Spears will take no prisoners when it comes to writing her new tell-all book, according to sources close to the popstar.

The Toxic hit-maker, 40, is preparing to put pen to paper after inking a deal with Simon & Schuster in what is believed to be “one of the biggest deals of all time”.

“Britney will hold nothing back in the memoir,” an insider told the latest issue of Us Weekly.

That includes setting the record straight about claims made about her by younger sister Jamie Lynn Spears, 30, in her own recently released memoir.

The singer has been locked in a bitter online feud with her sibling, with both resorting to calling in lawyers.

“Britney feels extremely betrayed by Jamie Lynn, as she has expressed publicly,” the source explained. “She will lay out that without her, Jamie Lynn would have no career.”

And it’s not just Jamie Lynn who will be needing to look over their shoulder, Britney has previously stated that she wants to “sue” her family, but didn’t specify which members she meant.

She will also be sure to lift the lid on the controversial conservatorship that she was finally freed from after thirteen years last November.