'Real Housewives of New York' Stars Ramona Singer, Dorinda Medley and Bethenny Frankel React to Luann de Lesse

Plus, Bethenny tells ET she definitely won't be at the wedding.

Luann de Lesseps is headed down the aisle for a second time -- and her Real Housewives of New York co-stars can’t believe it.

“I think we were all shocked when Luann told us she was engaged,” Ramona Singer tells ET.

“It was so quick,” Dorinda Medley adds. “I get that at 21, 22, but at our age? It doesn’t usually happen that fast, does it?”

Luann’s boyfriend, Thomas D’Agostino, popped the question in February, after just a few months of dating. Following the proposal, Luann’s rep revealed to ET that the reality star considers the businessman her “soul mate,” and is “over-the-moon in love” with him.

“All I know is, more than the engagement, there’s something else that transpires that you will not believe,” Ramona teases. “We couldn’t believe it. You’re gonna have to watch the show, because it is beyond.”

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It’s safe to assume Ramona is previewing the showdown between Luann and Bethenny Frankel seen in the season trailer, in which Bethenny confronts Luann with a series of accusations.

"You have sex with younger men,” Bethenny alleges. “You cheat, f**k younger guys, and criticize people about the same thing that you do.”

ET’s Jennifer Peros got Bethenny’s reaction to the engagement -- and the Skinnygirl mogul says she has no plans to be part of her co-star’s big day, set to happen in Palm Beach, Florida, on Dec. 31.

“I am not a bridesmaid,” Bethenny jokes. “I don't know if I'll be at the wedding … I think I have plans on New Year's Eve.”

“Luann and I have a couple bombshells [this season],” Bethenny continues. “One of them is one that I didn't want to drop ... you've seen it happen before, where there's just the day of reckoning where I just kind of come to Luann and say, 'Dude, come on. Like, own it.'”

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Ramona seems to agree with Bethenny, telling ET the cast isn’t letting anyone get away with anything this season.

“We’re all putting it out there,” Ramona says. “We’re calling you on it, you know? I kinda give the example, like, if you want to pretend you’re a pineapple, when we all know you’re an orange, just admit you’re an orange. And we’re calling everybody out on their stuff.”

When pushed about Bethenny’s allegations against Luann, Ramona said that was a perfect example of her orange/pineapple analogy.

We’ll have to wait and see how it all unfolds. The Real Housewives of New York airs Wednesday nights on Bravo at 9 p.m. ET.  We have a feeling it’s going to be the best season yet -- check out the video below to find out why!