Kelly, who is no longer friends with her fellow The Real Housewives of Orange County co-star, made the accusation against Meghan during an interview with E!'s Daily Pop.
Kelly vented about how a text-message exchange between Meghan and herself featured on the most recent season of The Real Housewives of Orange County -- which led to an argument on-camera -- was supposed to be "private conversation" and she felt it was "stupid" of Meghan to bring up "rumors about your husband that are out there that you know about."
With that being said, Kelly sniped to the Daily Pop, "It's like, I don't pinpoint her stuff out when she was having an affair with Jimmy when he was married to Allison. I don't put that stuff out there. Sorry, spilling the tea now."
Allison Jayne Raski was the second wife of Jim, a former MLB baseball player who has been married to Meghan for three years.
Prior to his marriage to Allison, Jim was also married to Lee Ann Horton.
However, a source denied that Jim and Meghan had an affair while Jim was still "romantically involved" with Allison.
"For people to insinuate that Meghan had an affair with Jim is completely bogus. Jim's second wife, Allison, was not romantically involved with Jim whatsoever when Meghan and him met," the source told E! News.
The text-message exchange shown on the recent Real Housewives episode was of Kelly and Meghan accusing each other of cheating on her spouse.
Meghan asked Kelly, who is married to her soon-to-be ex-husband Michael Dodd, if a certain mystery man in her life was her boyfriend, whom Kelly fired back is "like my brother."
And then Kelly accused Meghan's husband Jim of having a mistress when Meghan was about seven months pregnant with her daughter Aspen, whose first birthday is next month. The girls openly talked about the situation at a bar with their friends present.
Kelly announced in September she's going to officially divorce Michael after years of a roller-coaster relationship.
Five years ago, Kelly filed for divorce but never went through with the proceedings to finalize the paperwork. Her 11-year-old daughter Jolie Dodd, according to People, is relieved by her parents' decision to finally call it quits.