Begging For Advice 😣

So, about a month ago I began chatting to a guy who suffers with his mental health and has also abused drugs in the past.. He has since stopped. The conversations are constantly negative, we talked on the phone last night for the first time and there was literally no happy talk.. It was depressing. I also suffer with mental health issues and this is definitely draining me. I don’t want to push him away though because I’ll feel like a monster. It’s like, he’ll tell me when he starts to feel sad and I’ll try my hardest to make him feel better. He’ll take ages to reply, even hours. He’ll leave me on opened also for hours sometimes and I just feel like, why do I bother? I feel like I’m his therapist or something. I don’t really know how to get out of the route. Any advice would be amazing!