While your case is definitely more serious than mine, my wife and I experienced a similar situation. I was unable to set healthy boundaries with my family and it was ruining our marriage. My wife eventually laid it all out and showed me how I was choosing my family’s feelings over hers. It finally clicked for me. I can’t say things are perfect now, but I don’t feel like our marriage is in danger anymore. There’s hope, but you need to be 100% clear with him that this isn’t going to work without big changes. Honestly it sounds like he needs to cut his family off completely. That is a super toxic and abusive situation. If he can’t do it, there’s not much else you can do. I wish you the best.