Real Housewives of Orange County Reunion Sneak Peek: Vicki Gunvalson Gets Caught in a Lie over Brooks Ayers' Cancer

Orange you glad Vicki Gunvalson is finally coming clean?

In an exclusive sneak peek at Sunday’s Real Housewives of Orange County reunion finale, the “O.G. of the OC” turns a major corner when she finally admits to lying about embattled ex-boyfriend Brooks Ayers.

Gunvalson was under fire for most of season 10 for supporting Ayers as he claimed to deal with a cancer – a diagnosis many of Gunvalson’s cast mates actively questioned.

On Sunday’s episode, former friend Shannon Beador backs Gunvalson into a corner about a particular story Gunvalson told her about enlisting the help of Heather Dubrow‘s husband (and Botched star) Terry when Ayers was violently ill one night.

At the reunion, Gunvalson admits Ayers had actually insisted that she not involve the Dubrows, so she never called Terry – translation: Gunvalson lied to Beador.

“I fabricated it because I really was looking for compassion,” she admits.

When the ladies – including Gunvalson’s daughter Briana Culberson, who openly despised Ayers during his relationship with her mother – won’t let up, host Andy Cohen feels he has to point out: “That’s a very important thing … she’s admitting something to you guys. You’ve been accusing her this whole season.”

But, as Gunvalson has learned time and again this season, answering one question only opens the door for many, many more – most pointedly from sometime best friend Tamra Judge: “Why?”

Gunvalson admits, “I’m not sure why. He was getting so quiet-mouthed about including me on everything that I just wanted to say, ‘You know what, this is your baby. I’m going to work, I’m going to handle my family. If you have cancer, if you don’t have cancer …’ ”

Then, perhaps most shockingly of all – and despite splitting from Ayers in August – Gunvalson maintains, “I still believe he has cancer.”

The Real Housewives of Orange County

reunion concludes Sunday at 8 p.m. ET on Bravo.