This sounds really tough on you - no one wants to hurt someone who’s already down. It shows what a nice person you are, and how he’s obviously taking you for granted and maybe hasn’t noticed how it’s affecting you.
If the choice involves one option that is hurting yourself, choose the other. Life is too short. You shouldn’t stick with anyone who can’t make sure you’re happy, despite their own problems.
Suggest he seeks counselling and say you’ll be there for him and want to be there - but that as far as being his girlfriend goes, you need a little break, while he works through his family trouble.
The shock might be enough to make him come to his senses. It doesn’t sound as if you have a real bond or one that he can’t cope without - or you for that matter. Give yourself the space to look after yourself.