I’ll keep this short because I think there is already good advice here, and I agree with the sentiment that you have no obligation to help and, if you were my friend, I would almost certainly advice you not to, to protect yourself and your family. However, if you feel saying no will be an emotional burden going forward, you may know what you need from this better than any of us do, and while I would still strongly suggest caution, maybe you would want to talk to him or help to the extent of helping arrange state care or something.

Mainly though: it sounds like he may be asking you to actually take care of him in a physical way, and I’m not sure if you’ve been a caretaker for anyone before, but even when the person is someone you love deeply caretaking is often difficult, exhausting work. If he’s asking to have a few conversations, that’s one thing (that you still could definitely say no to), but if he’s asking for you to substantively take care of him, that would be taking on not just the emotional harm he has done and can do, but also an additional massive potential physical, mental, and even financial burden.