Kardashian Diary Lawsuit -- Ex-Stepmom Claims Suit Is B.S.

Ellen Pearson -- the woman who was married to Robert Kardashian when he died -- claims the Kardashian kids don't have a leg to stand on in their lawsuit against her for selling portions of their father's diary to the tabloids ... TMZ has learned.

Kim, Khloe, Kourtney and Rob Jr. all banded together last month to sue Pearson for profiting off the diary ... a diary that contained a slew of juicy personal information.

The Kardashian kids claimed in their suit that the diary was left to them in Robert's will, but in her response filed earlier this week ... Pearson claims that just isn't the case and the diary is rightfully hers.

Pearson also shoots down the idea that she hid the diary from the Kardashians, but she does fully admit to selling it to the tabloids and owns up to the fact that she got paid for it.

In the end, Pearson claims the Kardashians have no case and is asking a judge to toss it out completely.

A judge has yet to rule.