The 58-year-old explained Thursday why she skipped the Season 9 reunion following news she's quit the show.
Vanderpump spoke out on Twitter after a fan said they hoped she would appear in the episode, which airs July 16.
Vanderpump said she didn't attend the reunion because her co-stars were being bullies.
"No in season 4 & 6 it was whole cast against me, and I sat there 10 hrs. This year again it was 5 against 1. I was done, it was just too vicious this time, I wasn't in the same place emotionally. #BULLIES," the star wrote.
"This last year was a very negative year for me," she told Extra.
"I just had a horrible time with the show and the women. It was a very sad time in my life and it wasn't made any better. I just decided to walk away."
Vanderpump clashed with her co-stars in Season 9 over #Puppygate, a scandal where her co-stars accused her of leaking stories about Dorit Kemsley after a dog Kemsley adopted from her organization ended up in a shelter.
Cohen said in an interview with The Hollywood Reporter published Thursday that Vanderpump is welcome back on the show if she chooses.
"I think she know it's an open door and, like all these shows, the show will go on," he said.
"We will miss her. But there is a fantastic group of all-stars that remain on the show so I can't wait to see what happens next."
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