If G knew I had his wallet, I'd give it back to avoid a nasty argument. I'll admit it though, if he didn't know I had it I'd probably let him believe he lost it. I would take all the money out of the bank account, not to play god or control him but because it's my money too and we need it to live!
I'd probably call the ambulance as well. It sounds like your AH is making himself sick and it's not your job to take care of him. It sounds like he needs professional attention.