You sure were generous by dropping the support. You ex is a lucky man in that respect. I too, know about alcoholism and the difficulties it can cause for kids/teenagers when they are subjected to stupid behavior like your ex exhibited while "camping". No kid should have to go through that but unfortunately, it's all too common.
I don't know about the legalities of visitation in a case like this, but I agree with the many others who have stated that the choice should be up to your son. I think you made the right decision by telling your son to speak with his father about how he's feeling - he's old enough to have a man-to-man conversation with his father. If the father chooses to do nothing to make your son more comfortable being around him, then the father can live with regrets in the future. I have a feeling that if this did have to go to court, that a judge would side with your son. Being that he is predisposed to alcoholism, it's really bad parenting for his father and his wife to party in front of your son.
Let us know how everything turns out. Good luck!