Mary Cosby wed her late grandmother's second husband, Robert Cosby Sr., in an "arranged" marriage

Jen Shah Mary Cosby Real Housewives of Salt Lake City
Credit: Chad Kirkland/Bravo (2)

Jen Shah knows how to hold a grudge.

On Wednesday's episode of The Real Housewives of Salt Lake City, Jen lashed out when she saw her close friend Meredith Marks spending time with Mary Cosby — whom Jen still hadn't fully forgiven after their fight several weeks prior.

"I know you've been hanging out with Mary and going to her church and all this stuff," Jen said to Meredith at fellow housewife Whitney Rose's party. "And I'm like, 'Maybe she just doesn't want to hang out with me because she's friends with Mary, and Mary would get mad.'"

While Meredith tried to assure Jen that Mary wasn't coming in between their friendship, things quickly escalated when Meredith said she would not take a side in their argument.

"Are you serious right now? I've been your friend before you knew her," Jen said, becoming visibly upset. "I'm not saying you're supposed to be mean to Mary, but how are you my friend if somebody hurt not only me, but my family? That's not okay with me. Yes, it's hurting my feelings."

Things really took a turn when Jen insulted Mary's marriage — within earshot of Mary herself.

"You think she's a f---ing good friend? Good luck with that," Jen said. "You're going to go with Mary? Who f----s her grandfather? That's the truth!" (Mary wed her late grandmother's second husband, Robert Cosby Sr., in an "arranged" marriage. The two have been together for over 20 years and share a teenage son.)

Mary Cosby and Robert Cosby Sr. The Real Housewives of Salt Lake City
Credit: Bravo

While Mary didn't say anything, all the women agreed that Jen's comment hit below the belt and urged her to call it a night.

"That's just rude," said Whitney. "Whether it's true or not, that's just rude. Who talks like that?"

"I heard that," Mary said in a confessional interview. "Thank you for telling me and showing me who you are. You can call me whatever you want. Clearly, there's something about me that you find fascinating because I'm always in your mouth."

The next day, Mary said she didn't understand where Jen's hostility was coming from.

"She called me a 'grandfather m-effer,'" Mary said. "Apparently she hates me. She wants to be the big dog."

"I've been called a lot of different names, however never that," she added. "It does sting."

Real Housewives of Salt Lake City
Credit: Bravo

But when Mary announced her plans to throw a lunch with all of the women, she decided to invite Jen.

"I want to do this luncheon for us to hear each other. These women don't listen," she said. "I knew that if I didn't invite her, that would be negativity. I felt like deep down it was the right thing to do."

At the lunch, Jen tried to explain her outburst, saying she learned to value loyalty after growing up as a minority.

"When I say you're my friend, you're my f---ing friend. I'm crazy AF and I might go off, but it's because I love my friends," she said, offering an apology to Meredith. "No one reciprocates the type of loyalty my father taught me. I know I have a very hard exterior ... I just want you to know why I do that. I care so much."

But Mary felt her apology was missing.

"Where's my apology?" she said. "Jen calling me the 'grandfather whatever,' it's cruel."

The Real Housewives of Salt Like City airs Wednesdays (10 p.m. ET) on Bravo.