KATY Perry has been left heartbroken by her estranged husband Russell Brand — after finding out his latest plans.

According to Us Weekly, the British comic, 36, plans to cover all the nitty gritty, sometimes ugly details of their failed 14 month marriage in an upcoming memoir.

“Katy is insulted and feels betrayed that Russell has treated her so poorly,” a source said. “She will never forgive him. Ever.

“He’s being so atrocious that she feels like she never knew him.”

Previous reports claimed Katy and Russell hadn’t spoken about divorce prior to their split.

“Katy and Russell were having normal couple problems,” a source said.

“There was no talk of divorce around Thanksgiving. It all happened right before Christmas but no one, not even Katy saw the divorce coming.”