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Jill Zarin tells she still can't get over the frosty reception she received surprising Ramona Singer, Alex McCord and Bethenny Frankel on vacation in the Virgin Islands.

"It was such a Mean Girls moment that I literally cried for like two or three days," she tells Us. "They didn't offer me a glass of water or a bathroom! We had just traveled nine hours, and they knew it. I had to pee! You have no idea what a schlep it was. Schlep doesn't even describe it!"

Zarin, 46, originally told Singer, 53, she wouldn't go on the trip -- which was to celebrate Singer's marriage vow renewal -- because of her feuds with Frankel, 39, and McCord, 36. But she tells Us she decided to swing by on her way to St. Bart's to declare: "'I'm here to make up with everybody!'"

Zarin says Singer and McCord refused to give her a chance to explain.

"Alex was the one to really throw me out," she tells Us. "If she said, 'I don't care‚' then Ramona would have had me stay. [And] why didn't Ramona say to Alex, 'Jill is my friend. She should have called, but I'm not throwing her out'?"

Says Zarin, "It was the most hurtful thing that's ever happened to me."