Kardashian Ex-Stepmom Sues for Defamation -- Kris Jenner Is 'Manipulative & Devious'

Kim Kardashian's ex-stepmom Ellen Kardashian has just sued Kris Jenner and the Kardashian sisters for defamation, claiming the K-fam is on a mission to make her look like a bitter gold digger -- when they're the ones who should be ashamed of themselves.

Ellen filed the suit against Kris, Kim, Khloe, Kourtney, Rob, and even Ryan Seacrest Productions -- insisting the girls and "Keeping Up with the Kardashians" producers attempted to ensnare her in a recent plot line on the show, involving a private investigator attempting to hawk damaging information about the Kardashians.

According to the lawsuit, the investigator attempted to sell the information to Ellen -- in order to make her look like some kind of black mailing scumbag -- but Ellen refused to take the bait.

Ellen says the Kardashians trashed her on the show anyway, making up lies about her to fit their anti-Ellen agenda, such as accusing Ellen of marrying Kim's dad Robert Kardashian for his money -- and Ellen's lawsuit gets downright nasty.

Ellen -- who was married to Robert Kardashian before he died -- calls Kris Jenner a "manipulative and devious mother and ex-wife who simply used and exploited her children." She also calls the family's careers meaningless.

FYI, the feud between Ellen and the Kardashians has been raging for years ... it's nothing new.

Ellen is suing for unspecified damages. Calls to the Kardashians weren't returned.