The fight began with recycled drama from an earlier episode this season when a tense dinner at the Palihouse in Los Angeles between the three left Vanderpump storming out of the restaurant.
Since the nasty fight, Kemsley has gone behind Vanderpump's back claiming to the other housewives that the dog rescue owner was "jealous" Kemsley paying more attention to Richards than to her.
Additionally, Kemsley previously pissed off Richards for trying to stir up drama between her and Erika Girardi during a getaway at Teddi Arroyave Mellencamp's beach house.
On last night's show, Richards' claws came out. The housewives attended a Bella Magazine party where Kemsley was the guest of honor – and Richards took it upon herself to confront Kemsley for the slew of fights she had started.
"Why would you try to go hurt me and hurt Lisa by saying things against us?" Richards called out Kemsley.
A confused Kemsley asked Richards what she was referring to – and that's when Kim Richards' little sis went on an expletive rant.
"I'm f—king pissed off," Richards screamed in Kemsley's face. "Things were said about me and Lisa Vanderpump that should have never f—king been said! I've never f—ked you over. I've been f—ked over."
Wide-eyed Kemsley was left in shock while Vanderpump did not say a word.
Richards expressed frustration to the camera about Vanderpump's nonchalant attitude. "She makes me look like an idiot!" said Richards.
Tensions boiled over when the group decided to leave and Vanderpump offered to ride home with Kemsley. This prompted Richards to then confront Vanderpump for not appreciating her loyalty.
"If I had done this it would be a huge deal and for some reason Lisa refuses to admit that what Dorit did was really wrong," Richards told the camera. "It feels like a slap in the face."
Richards then accused Vanderpump of kissing Kemsley's "a—."
The dramatic night ended with the ladies back at their hotel where Richards and Vanderpump refused to make up.
Also in the episode, Girardi met with book publisher Simon & Schuster to discuss her upcoming book.
"Here's the kid from Atlanta who had a dream and didn't have anything, and now I'm sitting at Simon & Schuster," Girardi excitedly told her book editors. "I'm beating the odds so there's no room for mistakes."
A sneak peek of next week's episode shows Vanderpump and Richards' drama picking up, as well as a confrontation involving Real Housewives of New York star Bethenny Frankel.
The Real Housewives of Beverly Hills airs every Tuesday at 9 p.m. EST on Bravo.
We pay for juicy info! Do you have a story for RadarOnline.com? Email us at firstname.lastname@example.org, or call us at (866) ON-RADAR (667-2327) any time, day or night.