Danielle Staub's Ex to Sue Over 'Naked Truth'

It's all over Danielle's tell-all book "The Naked Truth" -- in which Staub allegedly claims Kevin Maher was "incarcerated for 18 months" for "criminal activity relative to Danielle Staub."

Maher tells us the claim is "patently untrue" -- and insists that before the book came out, he warned the publisher, Simon & Schuster, that if they published the book ... he would fire off a big, fat lawsuit.

But they published it anyway -- and Maher is pissed ... telling us he's getting ready to hit them with a $10 million lawsuit.

As we previously reported -- Kevin just settled his defamation lawsuit with Danielle over some pretty nasty things she allegedly said about him ... and we're told he walked away with a pretty nice payday.