This sounds great and very mature that you and your ex husband have been able to co-parent and remain friends. However, it seems like one, or both of you, hasn’t moved on. If you’re not thinking about getting back together then I would cool it with the open house policy. I get that he wants to see his kids, but he can take them to school or pick them up when it’s time to visit. Hanging at your house will definitely kill your social life, which may be just what he’s trying to do. Funny you don’t mention you busting into his house and having an open door policy. Most likely he wouldn’t like it because I’m almost sure he has some monkey business going on, otherwise you would have never left. Get some boundaries.