Personally, I think family need to decide who they are going to support and how. Because it seriously compromises the healing of their family member if they just KEEP ON SEEING the ex. If there's children involved it's different. But when there is no children,then I don't understand why there isn't a clean break for everyone's sake.

Going through a divorce is horrendous. Having to confront your ex in your life all the time is like picking the scab off a healing wound.

I'm really sorry your step-mom hasn't figured this isn't particularly helpful for you.