Here's what happens down the road, though, jodi. You've vented and purged and you feel GREAT!!!!! EVERYONE knows how you feel about the homewrecking witch, because you've told everyone - over and over. And in the beginning, everyone sympathizes with you. Yes, he is a jerk. Yes, she is a homewrecker. Yes, they should burn in hell. And so on and so forth.
But, a few months or years later, you start to become..."the bitter ex wife." No matter how innocent a party you were. No matter how badly he (or they) behaved. No matter what. People start to say, "Boy, don't get her started...". Then they start to avoid the subject altogether. Then they start to avoid you.
It's the double whammy of all double whammies. Not only are you the innocent victim, but you get blamed for any (natural) bad reaction.
BUT, if you can treat "her" decently, you will be the better for it. Mild, pleasant casual contact, and brief but pleasant conversation, while at the same time showing no real interest in or curiosity about her life or anything she might have to say.
Little children don't have the capacity you had as an adult - they barely understand anything that is happening to them. My younger daughter asked me if I knew her stepmother before she and dad got married. She was almost 12 at the time, and we had been divorced since she was 4. She asked me this even though the stepmother and I had been best friends for the first 4 years of her life, and the stepmother's daughter had been my older daughters' best friend all of her life, and we had all eaten dinner together at a local restaurant every Friday night for those years. When I pointed those things out to my daughter, the wheels started turning and finally she looked at me and said, "Wow, Mom, that's harsh."
She just couldn't comprehend what had happened - and didn't even remember that we had known each other "before."
Later on, children DO understand, believe me. DD19 has a cordial relationship with her father, but I wouldn't call it close or loving. She would say he is not really an important part of her life any longer. Of course, his decision not to continue child support for her younger sister and not to contribute to any educational expenses had something to do with that as well.
I'm not saying you can't tell the new wife exactly what you think of her - once. Or even twice if need be. But to keep on antagonizing her and acting like a child doesn't ever, ever help in the long run.