I’m in a similar situation, it’s so hard knowing whether leaving is the right thing to do. If you have done everything you can to help him, then there’s no more you can do then hope that this will be the point he realises he needs to get better, sometimes we don’t realise we are enabling the ones we love and think we are doing the right thing by protecting them, when we are just giving them a reason to not get better. If your support is being used as reassurance that their actions are okay, rather then using it to better themselves, I think this is when it’s time to leave, as horrible as it is. You have to look after yourself, and you don’t need to feel guilty about that, I hope everything works out for you x