Robert Kardashian's widow Ellen recently released Robert's old journals . . . which reportedly included a story about Kris Jenner beating up Kim Kardashian when she was 9 or 10.

Well, the Kardashian girls are fighting back.

Khloe Tweeted, quote, "How can such a piece of trash even mention my father's name. You married him on his deathbed when he was not even aware of his surroundings.

"You should be hiding in shame for all of the lies you sell to the tabloids. You have no right to even mention our names especially my mother's! We don't know you!!! How dare you spread such lies! You are a disgrace."

Kim added, quote, "10 yrs since dad passed & this woman he married [for] 2 wks before he died needs to get a job instead of trying to destroy my family [with] fake stories."

Then she said, quote, "PS that story that my mom beat me & threatened to kill me hahahhahaha! I'd beat her! [Just kidding] truly laughable!"