Have no clue what to do

Two weeks ago, I reconnected with an ex boyfriend. We decided to give a relationship one more try. He was diagnosed with HIV around the same time I was, too. He had been battling with the fact that his life has taken a very different direction. During the time we were apart, he also got hooked on drugs. When we met again, he told me he was over it. But, this last couple of days, he had been feeling depressed. On Sunday he went out and got home the next day (that's what his sister told me). When he woke up on Tuesday, he texted me saying something so random that I didn't believe. Yesterday night, he called and explained to me what really happened (as far as I know). I texted me this morning saying that it would be better if he deals with everything he's going through alone. He doesn't drag me down along with him. I don't know what to do. He seems lost but he doesn't want to be helped. I don't want to leave him to deal with all this by himself. However, I'm also trying to put my life together by keeping myself healthy and on the right track. What should I do?