Harry Hamlin and Lisa Rinna Slam Nicollette Sheridan's Denial She Cheated with Michael Bolton

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Harry Hamlin and Lisa Rinna are standing by their claim that Nicollette Sheridan cheated on Hamlin with Michael Bolton.

The allegations against Sheridan were first made on Tuesday's episode of The Real Housewives of Beverly Hills, when Rinna, who has been married to Hamlin for over two decades, told her fellow housewives that Sheridan, 55, allegedly ended her marriage to Hamlin, 67, after meeting Bolton, 65, at a concert.

Days later, Sheridan fired back at Rinna, 55, on Twitter, slamming the alleged affair as "FAKE NEWS!"

"Harry and I ended our marriage nose to nose in Canada… Michael was a long time friend that was invited to our wedding… Happy Harry found happiness with housewife @lisarinna," the star wrote on Friday.

Sheridan, of course, famously starred on ABC's scripted series Desperate Housewives, which inspired Bravo's Real Housewives reality franchise.

Turning up the heat, Hamlin responded on Saturday, criticizing his ex-wife's denial and going on to claim that she allegedly stepped out on him two weeks after his mother's death.

Paul Archuleta/FilmMagic; Dia Dipasupil/Getty; Allen Berezovsky/Getty

"Re Fake News! What's it called when your wife of one year suddenly goes to bed with a pop singer? …two weeks after your mother dies?? I did a lotta stuff with my wife 'nose to nose' but ending our marriage was not one of them!" he wrote.

In support of her husband, Rinna replied to his tweet, "Sweetie @IamNicollette You're the gift that keeps on giving!"

According to ET Canada, Rinna penned an additional note on her Instagram Stories, which has since been deleted. "My bad, I'm sorry, Nicollette," she reportedly wrote. "I forgot to thank you also. Thank you for f—ing Michael Bolton and cheating on Harry while married. I thought I'd take the high road and not tweet this… NAH."

Darlene Hammond/Hulton Archive/Getty Nicollette Sheridan and Harry Hamlin

RELATED: Nicollette Sheridan Denies Cheating on Ex-Husband Harry Hamlin with Michael Bolton

Hours after Hamlin's tweet, Sheridan fired back once again, continuing to categorize the cheating allegations as "FAKE NEWS."

"Do you really want the truth shared?" she tweeted on Saturday. "I appreciate that you want to support your housewife's FAKE NEWS narrative, but the end of our marriage had nothing to do with anyone other than us. Sad you still can't own your part.@HarryRHamlin @lisarinna."

Reps for Bolton, Sheridan, Hamlin and Rinna did not immediately respond to PEOPLE's requests for comment.

The discussion of Sheridan and Hamlin's brief romance came about after Housewives newbie Denise Richards revealed to castmates Rinna, Dorit Kemsley, Teddi Mellencamp, Camille Grammar and Erika Girardi that her then-fiancé Aaron Phypers was still technically married to Sheridan.

That's when Rinna dropped a major bombshell.

"Harry was married to her 30 years ago," Rinna explained to the ladies, who couldn't help but gasp upon hearing the news.

"The story is, she went to a Michael Bolton concert at the Hollywood Bowl — and left with Michael Bolton!" Rinna claimed, prompting Girardi, 47, to yell, "Is that really true?!"

"F— yes! Harry was in Canada!" Rinna responded.

Michael Bolton and Nicollette Sheridan

RELATED: Desperate Housewives' Nicollette Sheridan and Aaron Phypers' Divorce Has Been Finalized

In the end, Rinna shared she's grateful things ended between Sheridan and Hamlin.

"I thank Michael Bolton to this day. Are you kidding me? Let's cheers to Michael Bolton! Thank you, Michael Bolton, because I would not have these beautiful children," Rinna said.

Rinna and Hamlin tied the knot in September 1997. They share two daughters, Amelia Gray Hamlin, 17, and Delilah Belle Hamlin, 20.

RELATED VIDEO: Lisa Rinna Shares Sweet Throwback Photo from Her Wedding Day 20 Years Ago

Last year, during an appearance on Watch What Happens Live with Andy Cohen, Rinna opened up about their relationship and how they've kept the spark alive over the course of their 21-year marriage.

"I don't really know. I really don't know the answer," she admitted. "I think that we are complete opposites. And I mean, we have nothing in common!"

RELATED: Lisa Rinna Celebrates 21 Years of Marriage with 'Soulmate' Harry Hamlin

"You know what you have in common that wildly comes across?" chimed in host Andy Cohen, 50. "You are crazy about each other."

"We are," said Rinna. "We are crazy about each other, and you can't create that, you can't make it — it either is, or it isn't."