Chic, I know your pain and don't have any quick fix answers. What if you insisted he apply for assistance or disability?
I don't know your relationship with him too well, but can you insist he be evaluated and get some help...while still living under your roof?
If he can get help and financial assistance with food and housing, then maybe the next step would be for him to move some place he could manage.
Forgive me if I over simplify a complicated issue, I just would love to see this all work out without breaking your heart.
You are both in my prayers every day. I hope that somehow he is willing to get some help.
Hugs