CrochetFanatic, if you're looking at what to do in the future, here are a few suggestions.
- If your uncle comes to your mom's house as a guest, be busy helping your mom with the hosting duties so that you don't have to interact with him much. Cook, set the table, clean up, invent things to do. Be too busy to sit down and visit.
- If he hosts, then don't go. If you and your brother feel that strongly about Uncle's shananigans (understandably), then it isn't appropriate to accept Uncle's hospitality.
- Once you move out, don't invite him over if you don't want to give him the basics of courtesy. In fact, I'd say it's a good rule of thumb that if you wouldn't shake a man's hand, you shouldn't be extending an invitation to him.