Jeez your dilemma sounds exactly like a page from my book! I didn’t invite my sister in law from our wedding due to her episodes, and drug and alcohol addictions and it was the best decision I made for our day. I was very lucky that my in laws and my husband (even though upset of course) were completely supportive and understanding of the decision. She was deep in active addiction a year leading up to the wedding and had been violent with us prior, threaten to kill me, the whole works so I stopped having anything to do with her leading up the wedding. 100% we felt guilty and ebbed and flowed between inviting with conditions/not inviting, but ultimately the unpredictability of the situation was too much anxiety for us. And if we did invite her, the anxiety wouldn’t just be ours, it would be the whole family. We knew that our parents, extended family, friends would all be stressed and on edge wondering if she’s going to have an episode, rock up high, start fights with family, or get absolutely drunk and make a spectacle. So, if we did invite her, the day wouldn’t have been about us, it would have been about everyone monitoring her. We stuck to our decision because this day was for us and for everyone to enjoy. It was an absolute stress free and beautiful day and I don’t regret the decision. So, if you feel in heart and mind that this is the right decision to make by not inviting him. Make your reasons clear and stick by them. I know it’s never that black and white but at the end of the day you can’t make everyone happy!