Problems With A Friend

So my best friend is suffering from anxiety/ depression and its gotten worse lately. He is having problems with an ex girlfriend and Ive been helping him to get through it. Im basically the only person he talks to. I love him like a brother but I feel like the relationship borders on toxic. He constantly belittles me and gives me anxiety just being around him sometimes. Recently he confessed that hes in love with me which gives me even more anxiety because a) Im not into him and b) hes done this before and it nearly ruined the relationship when I rejected him the last time. I told him I didnt have feelings for him and his reaction was to guilt me. Saying that he would put his negative feelings aside to still be friends, but the way he said it made me seem like a jerk and him the victim, even though just knowing he feels this way about me makes me uncomfortable because my nerves. I told him I need space, which he didnt take too well. Ive decided that I dont really want to be around him anymore because he constantly makes me feel bad, but when hes having problems he refuses to go to anyone else. I feel like if I dont always keep him from the edge hes going to do something to himself. But doing so is hurting me emotionally. I dont know what to do anymore.