Confused with his mood swings

I started dating my sisters ex husbands brother about 8 months ago. At first I didn't tell my sister because she is very controlling on my life. Time had passed and I could tell it bothered him so I finally told her. Throughout our time together he would have mood swings he is a Cancer and from what I have read this is common for them. He also told me along the way that he had demons and that he hasn't been happy for a year. He had a very bad breakup with his sons mother whom him and her we're together for 10 years. I always asked him are u sure u are over her, he would say yes. Little things would happen where we go into small fights and he said with his past of getting left and cheated on and my past that we would have issues. He also told me he wasn't ready for a relationship. Back in May he told me he couldn't be who I wanted right now, so I told him are u trying to be my friend or what? He would ignore it and I went to confront him and person and I told him I am ok with walking away today as friends and he didn't want that he said let's find a happy medium. After this time his ex had a baby in June and I think that made him depressed and I hadn't seen him since May. We started fighting because I felt he wasn't into this and I was wasting my time. The wknd his ex had her baby we had plans and he disappeared and the next day said he fell asleep, I knew the ex had the baby so I straight out said u sure u aren't depressed that your ex had a baby? He got upset and said I don't want her and I don't care. Come July we still hadn't seen each other and he claimed his phone wasn't working on and off so he would write me on Instagram. By Early August I am now feed up and he told me I'm not happy and I can't date u right now in my life. Then he would through mixed signals I started getting a little worried and contacted his mom and when I did she told me that he has been depressed since she left but he has many chances to get back with her and will not. That he talks about me a lot but that I want more than he can offer me. After this I'm trying to just be a friend he told me he wanted to be left alone and that I didn't have to be loyal. I found this hard because I knew he was severely depressed, many times I wanted to show up at his place and just comfort him. I offered to pay for his counseling because he was barely getting by. Throughout our time he would say he felt like less of a man because he didn't have much money and I had a career and was successful I spoke to his mom again and told me more in detail that he hasn't been the same since his ex left he is depressed that his exes new bf spends more time with his son. Which is not really the case they have about 50/50. Myself having 3 kids and being divorced I understand the feeling but not sure why he would pump the breaks on a new relationship due to this. He had told me his phone couldn't make calls because he dropped it in water but his mom told me that she spoke to him via his cell. By this time he would send me two words on IG every 4 days and lastly I hadn't heard from him in a week and we hadn't seen each other since May, I sent him something saying that I can't stick around when he is pushing me away I'm putting my life on hold for someone that isn't sure he wants me around. I unfollowed him on IG because I didn't want to see what he was up to. After this he had a picture that we had convo on that he wanted to see me a few weeks back I saw he deleted any trace of me and that really annoyed me so I simply wrote on the picture. Now we are deleting comments? After that he deleted the comment and blocked me off of his IG he has also blocked me from his cell. His mother spoke to me and told me he is even being ugly to her and is upset with her. I feel bad because I want to be here for him but i can't deal with someone that isn't over a past relationship it isn't fair to me. As I said I have offered him professional help and he said no one can help him. He has shut down to everyone and I'm worried he might do something to himself. I've voiced this to his mother and she just said I have told him to get help. What keeps me holding on is I know he cares but he is just not in the right mindset, also one of his brothers committed sucide and this scares me to no limit that it might run in his family. As I am blocked from all sources I sent him something from an app that change my number and told him I don't want to leave his life and I miss him a lot let's talk and not ruin things between us because we are both hurt. He has yet to reply. What should I do?