Before Dorinda Medley was fired from RHONY, she and her former castmate Tinsley Mortimer duked it out at the Reunion.

There, Tinsley revealed the real reason that she and Dorinda don't get along -- and the audience saw unseen footage for the first time.

There was so much at the The Real Housewives of New York City Reunion on Thursday night.

One highlight was Leah McSweeney wearily trying to explain to Ramona Singer how virus safety guidelines work during a pandemic. It was like talking to a wall.

At one point, Ramona began chanting "I don't have the virus" repeatedly, like a magical incantation to ward off viruses and critics alike. It doesn't work like that.

But after that (and a lot of talk about alcohol), the focus shifted to Tinsley -- who has left the show but who did show up for the Reunion.

"Scott did not make me choose between him and the show," Tinsley clarified.

Famously, she quit the show to move to Chicago with Scott Kluth, to whom she became engaged last November.

"I knew that the show was definitely an issue for him," Tinsley acknowledged.

She recalled: "I knew that when we got back together it was a decision that I had to make."

"I chose him over being here with everybody," Tinsley emphasized.

"I didn't want to put him in the mix of all this," Tinsley stated.

She explained "because it could be toxic and it could be bad for my relationship."

Infamously, a lot of relationships feel extra pressure and scrutiny when they are featured on reality television.

Andy asked if Tinsley and Dorinda have spoken since Tinsley's departure from the show.

"No, of course not," Tinsley replied.

Meanwhile, Dorinda stated that it was her understanding that Tinsley had only spoken to Leah since leaving.

"We were actually friends at one point," Tinsley recalled with a tone of bitterness.

But she made it clear that that is no longer the case (obviously), and even brought up a major sticking point for her.

"The vile turkey baster comment," Tinsley accused, "when women cannot get pregnant and the infertility ..."

For what it's worth, Dorinda did apologize for the comment, which she characterized as a bad joke.

"Are you having a problem getting pregnant?" asked an incredulous Dorinda.

"No," Tinsley fired back, "but I am shamed for wanting a child."

"I'm surprised you don't have one already," Dorinda jabbed, "You've been talking about getting pregnant for so long."

Andy asked Dorinda directly: "What is your issue with Tinsley?"

"I believe half of what I hear in life and all of what I see," Dorinda replied. "You guys saw just what was on the show. There was a lot of stuff that went on."

"What happened was, after [Scott and I] had broken up, when we were in Miami -- this was season 11," Tinsley explained.

She recalled: "you and I got in this horrific fight that was not on camera."

Tinsley explained that the fight was "because I had told you that Scott had generously given John [Mahdessian] (Dorinda's ex-boyfriend) some money that you did not know about."

"I don't know why we're talking about John," Dorinda replied.

"The betrayal that you felt for John manifested to anger towards me," Tinsley theorized. "You took it out on me. You called John screaming."

Dorinda countered: "It's just not true."

"The producers did not want me to stay in the house that night because you were going so crazy," Tinsley claimed. "They were worried for my safety."

She accused: "You turned on me that moment when you found out John had that money."

"No," Dorinda assured Andy and the audience about Tinsley's theory, "I didn't even know about that."

At this point, viewers were treated to some intense footage of Dorinda on the phone with John.

The venom in her tone was fairly palpable.

You can see this previously unseen footage and more of their discussion in the clip that we have included with this article.

"I did nothing to you to make you hate me the way that you do," Tinsley insisted. "Your jealousy, your hatred, your obsession with my relationship."

"Hey, girl, I'm engaged. We're getting married ..." Tinsley began.

"With no financial security," Dorinda quickly interrupted. "Tinsley, I'd hate your life."