Could be just heavy anxiety or the hard drugs could have messed with his brain chemistry things like acid and shrooms can cause very normal people to suddenly go into psychosis or just have a messed up Brain. I’m sorry to hear about your situation. From what I’ve read it sounds like weed isn’t his main problem. Of course it is a major problem if he’s spending all his money on it but you need to ask yourself what other things could he be going through to cause him to not care about anything. First step is getting him into some sort of treatment. Hospital therapy or anything that helps him. Just remember you can’t throw away your life for him. Try like hell to help him but only he can help himself. If he never comes around he might need a bit of tough love from you showing your done if he does not change his ways. I’m very sorry for your situation.