Welcome to SR,
I am sorry for what your going through. Though is seams like you have learned that NO is a complete sentence. We never know where each of there bottoms are but giving money only prolongs and allows them to continue using. He is an adult and he has to make his own money, his own place to stay. He will not do it if you keep giving.
It is the hardest thing to turn them loose, let go and let God. But it is the best thing for them. All I do now is offer advice and love. When they ask for money I tell them I get a paycheck form a job they should try it. But this bank is out of money for them. ( Having two AS's 31 & 32)
I know your son knows how to survive but I will pray he finds the light and help for his disease. I hope you also seek help through Nar-anon.
Keep reading and posting, be well