Kardashian Family Sues Over Juicy Diary

The Kardashian kids are suing their dad's widow, claiming she's been illegally selling portions of a diary they inherited.

Kim, Kourtney, Khloe and Rob Jr. are suing Ellen Pearson -- who was married to Robert Kardashian -- claiming Robert had a diary that contained very personal details about the klan and has been selling tidbits to tabloids.

The deceased Kardashian -- famous for repping OJ Simpson -- allegedly left the diary to his kids in his will.

Among the info that Ellen allegedly sold -- Kris allegedly hit Kourtney and Kim and also threatened to kill Kim ... and Rob was locked in a car while Kris was out on a date.

The lawsuit alleges the diary is owned lock, stock and barrel by the Kardashian kids and Ellen is infringing on their copyright.

The lawsuit demands the return of the diary and family albums, as well as damages.

Interesting fact: Robert did NOT include ex-wife Kris in the diary inheritance -- just their kids. But Kris is listed as a plaintiff. It's curious -- Kris is NOT suing Ellen for defamation, for putting the brutality allegations out there. So the questions -- did Robert Kardashian make the allegations against his ex, and are they true?