AITAH to tell my husband his son is no longer welcome in our house

I married a great guy 40 years ago. He was a widower with an 8yr old son, Sean. It was my first marriage. I had no kids. Sean started calling me mom (his choice) a few weeks after we married. So I had an instant family, and we did lots of family things. Birthday parties, Disneyworld, camping, etc. Sean is now 49 with two kids and a wife. He has done a few tours (Army reserves) to Afghanistan, Bosnia, etc. Something has changed in his attitude toward me over the past ten years. I cannot pinpoint exactly when it started. He shows up at family gatherings and does not greet me, or even acknowledge me. We go out to a restaurant with him and his family to celebrate a shared birthday between Ray and his daughter. Sean does not talk to me. I am completely invisible. I have no idea what I may have done or said, but it has not gone unnoticed by others. My husband (Ray) is stumped too. I asked Ray to try to find out what is going on. Sean did not have any explanation (according to Ray) so it got dropped. I then asked Ray to tell Sean to straighten up when he is around me, and to treat me with some respect. The tension became uncomfortable enough that I would make sure I was gone when Sean came over, sometimes for an entire weekend. Sean will invite Ray to the grandkids’ activities at school, and Ray has gone on camping trips with them. This 4th of July Sean and his kids came to our lake house for the weekend. I was not thrilled that Ray invited them. I was not able to leave and had to spend the weekend in a small house with Sean and his family. Turns out Sean has developed an enormous beer habit, which means frequent trips to the only bathroom in the house. And every time he came out of the bathroom, the lid and seat were not put down. We didn’t raise him to be like that. I kept putting the seat back down, only to find it up every time he used the bathroom. Sean brought snacks for him and the kids. Bags of chips torn open and left open on the counter. Nothing put away. I pulled Ray aside and told him to address this with Sean. And then I asked if Sean was always like this when he visited. Yes. Ray admitted that Sean is a pig, and that it bothered Ray also. And Ray had never once mentioned to his son to pick up after himself and remember that he was a guest in our house. He just kept his mouth shut and let it happen. That’s when the lightbulb went on in my head. Sean has no respect for his dad or me. By staying quiet, Ray has passively let Sean know that his behavior is acceptable. So now I have discovered that Ray’s interpretation of addressing Sean was to ask him if there was something wrong. I am fuming and I am so done with being treated like this. I’ve given up on having a relationship with Sean, but now feel like Ray threw me under the bus. So I told him his son is no longer allowed in our house. AITAH? Overreacting? Expecting too much?