I appreciate all of the thoughtful responses to my last post. From talking with friends, reading and listening here, I have gained some insight. My good friend gave me a simple solution: ask yourself this, "Would this make my SS uncomfortable?" It's an easy way to gauge if my behaviors are appropriate or not. Would my SS be uncomfortable if I volunteered for his school? Would he care if I chaperoned a fieldtrip? Of course not. Would he be sad if I talked poorly about his mother? Yes... the answers are easy. It's about how it affects my SS. I don't need to cater to her feelings, because to be honest, I can't trust if they are genuine or manipulative. I will at times cater to her simply out of respect and to keep things moving smoothly. My DH puts up with a lot of her shit so as not to make waves. He gets to see his son more than what is on paper and he wants to keep it that way.

The Idiot's Guide to Stepparenting pointed out that YOU pick the role of the kind of stepmom you want to be. You can choose to be extremely active or not at all, and more like a roommate. (Obviously these roles vary with the ages of the kids involved.) I've shaped this role for myself. My DH made it clear in the beginning that he would not try to make me take on his responsibilities, and all he expected is that I would be nice to his son. Turned out, we got along famously and then only naturally, I've embraced a maternal position when he is at our house. I never do anything to lessen her importance; I try not to bring her up at all. But if my SS brings her up, "Mommy and I did this..." or "At my Mommy's house I..." I try to engage the comment for a bit so he can feel comfortable talking about her. There is no need for him to sense animosity.

During the heated convo, my DH told his ex that I was trying really hard not to step on toes... by reading books and joining an online forum. Her response, "Well, she doesn't have to do all that. All she has to do is be nice to him." I mean... CMON! She should be grateful I'm trying to be a good stepmom - it benefits her, her son and her family. She also said it was unnecessary for me to spend time alone with my SS. She said, "He spends time with you, because he misses you. If he doesn't see you on the weekends, he misses you... not her." Little does she know that just the day before, I was out of town and my SS asked for me several times and said he wished I was there! She doesn't comprehend how much we do together. And while I don't take time away from my DH and his son, he works a lot during the day so sometimes we go to parks, or museums, or do crafts. It's still easier for my DH to see and have access to my SS this way. I understand that she is just having a hard time adjusting to another woman being important to her son. But there will have to come a day when she respects my position and doesn't pawn me off as an "art buddy".

In short, I've made my role and I'm sticking to it. As long as I'm not doing anything to hurt my SS and nothing to purposely hurt the EX, there is nothing wrong.