The Real Housewives of NYC - Alex McCord, Jill Zarin

After three seasons of Real Housewives of New York City, Alex McCord has been, comparatively speaking, the calm, collected one of the group. But fans are about to see a new side of McCord when she and Jill Zarin butt heads in Thursday's episode (10/9c on Bravo).

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"Jill has taken every opportunity over the last three years to belittle my husband, my children and sometimes me. I really don't care about what she says about me, but I care about what she says about my family. It's just unacceptable, and I couldn't let it continue," McCord tells TVGuide.com. "By ignoring her, she began to think everything was OK, and she could go ahead and continue to make fun of the kids or get LuAnn to make fun of the kids ... she's a master manipulator."

Fans saw a more assertive side of McCord at the end of last week's episode when she "delivered a message" to Zarin on behalf of co-star Bethenny Frankel, in which Frankel says she wants nothing to do with Zarin.

"I didn't expect to deliver that message in front of everyone. It was one of those things where there was this pause and I realized it's now or never," McCord says. "In the end, I didn't say anything to Jill that she hadn't said to Bethenny over and over again."

Though the mother of two says she carried a lot of pent-up anger toward Zarin, it was what Zarin did the day Frankel's pregnancy leaked to the media that sent McCord over the edge.

Check out photos from The Real Housewives of NYC

"Jill called me pumping me for gossip. She did not care about Bethenny. She did not care about the pregnancy. She cared about the gossip. It really made me see red," McCord says. "And when Bethenny told me she had been calling the press on her behalf, I snapped a little bit."

Though there's only a handful of episodes left in the season, McCord says there's still plenty of drama in store — especially during a girls' weekend.

"I always thought, after Season 1, for a guy to crash a girls' party is not acceptable," McCord says. "Well, you might see that happen again. And it's not Simon!"

Are you on Team Jill or Team Alex?