Hi and welcome stwa
this is a guy you dated for a month then didn't see for 5 years and have seen a handful of times since, right?
I'm sure you care for him. I'm sure that deep down he's a great guy - but for now all signs point to this guy being chaos - right now and for the forseeable future.
The more you hang with this guy the more chaos will be introduced into your life.
There are any number of people - professional or experienced people who can help your friend - if he wants help.
Don't get into something over your head.
If chaos is not what you want then your decision is clear, I think.
D