[magnetowasright]

Others have rightly warned about taking on too much responsibility for your housemate, but I think there's more room for nuance as to whether becoming nursemaid is 'inevitable' or other such suggestions that it's immediately time to move out or whatever. Other commenters suggesting ultimatums (ultimatums are the worst way to deal with any personal situation imo) or that you'll end up embroiled in being his carer are a bit reactive, or maybe extreme?

That said, if moving out is what you want to do, that is absolutely what you should do, 100%. You don't have to justify anything about that decision to anyone.

If your housemate has been great for 5 years and you've been friends for 10, and if you are happy with your living situation and could see yourself still living there with him when he's stabilised, setting some boundaries around when you will contact his family or the crisis team like 'I will call the crisis team if I see you getting worse over the weekend again' (for example) can help you draw the line of what you can cope with and what you can take on. It can free you of having to make those tough decisions in a crisis again. It doesn't have to be you becoming his carer. Coping with this doesn't necessarily have to blow up your living situation or friendship, though, and I think that there's possibly options to explore for how you move forward and look after yourself than becoming his carer or moving out. Do what is best for you.

Good luck with it, and look after yourself!