I agree to set some firm boundaries. Unless you are ready to adopt this person, he needs to know that you have your own life and it does not evolve around his treatment. I had a similar situation and I was also nice in ways which you deemed supportive. Before I knew it I was expected to call and make regular meetings with my friend. This was my first encounter with such a person. I have never had a friend who would want to call every day, or even every month. I don't need that much contact with my friends nor do I want it. For me meeting a friend once every three months is ideal with calling twice a month. I have lots of friends and I don't want to have obligations with any one in particular. I am going through sort of the same thing with a girlfriend now. She was going through a rough time and I did one nice thing for her and she basically harassed me for two weeks.