As a divorced mom what things "piss" u off about your childs new "stepmom"?

I am the soon to be step-mom, and I can't do anything right. The ex-wife had hated me since day one...actually she clearly didn't like me before we even met. She told the children that they didn't have to listen to me and that I was a mean person. She also tells them not to interact with my children. She won't talk to me at all, every time I try to make small talk she gets short with me. She speaks negatively about me to others including her kids. Whats strange is that she left him, so I'm not sure why she is so angry. Maybe b/c she hasn't moved on or found someone yet, I don't really know. I have been taking the high road and not saying anything negative about her, if asked, i just say that I don't really know her well and I'm not going to judge her. We live in a very small town, but I never knew her prior to me dating her ex. I love their children just the same as my own, I feel for them, I know it hurts them and I believe it is wrong for a parent to speak negatively about the other parent or the other parents partner. Its not good for the children and they after all are whats most important. You don't have to like or be friends with each other, but you should be civil for the kids sake.