Step son and family

I am at my wits end. I have a step son that we are all convinced (including his GP) has Bipolar disorder. He is 22 years old, and had been in an eight month depression, never coming out of his room, refusing medical treatment, etc. We finally talked him into going to the hospital (with the help of a psychiatrist) but he was released 3 days later, with the simple diagnosis that he was just a "chronic marijuana user", and that he should deal with it.

After this 3 day hospital stay, we noticed a change that we thought was positive...he came out of his room, began socializing, began acting "normal"...just like his old self.

However, just a couple of weeks later, he really started abusing alcohol, and started being irrational. He beleives that he is becoming a millionaire, has moved into his pickup truck in a nearby town, refuses any criticism or reality checks, and when he comes home, is rude and disrespectful. My wife and I are mad at him when he is home, and worried when he is gone. It really is a hard thing to deal with.

Help???

We do not give him money. At the onset of this, he had a healthy bank account, but has since exhausted it, in only about 6 weeks. The only thing that I will give him is food, at a restaurant, and make sure that he eats.

Because of the disrespect he shows at our home I am contemplating telling him that he is no longer welcome, unless he gets some help, respects the rest of his family and our house, and is sober.

The fear that I have is that he may fade into a bad "scene", or worse. Making things more complicated is the fact that his estranged father is being treated for depression, and that his uncle committed suicide some 9 years ago. This is in his family, and has reared it's ugly head for him now.

But I do have the rest of the family to care for, and "his" problems become the problem of all when he is here.