I can relate to the pain of your break up, but not all the chaos. I had some of that, but not to that extent.
If you chose to move in with a man who was so obviously sick, you need to take a hard look at your codependency. You say you're worried about him, but you need to be worried about your own self or else 1) you will take him back or 2) you will find the next addict to fill your void.
I know your pain OH so well. I left my ex A 3 yrs ago because he was a seriously demented narcissist and had my head so messed up, I didn't know what day it was. It took me a year to get fully over it and 2 yrs to come out of the fog.
My best advice, get to al anon and therapy and if you do take him back, never stop al anon or therapy