I have couple of issues right now, but I will start with a brief back story of how all this started. Last year around this time me and my boyfriend of 4 years now were going through some tough times in our relationship. We were barely talking and meeting each other. I was in school and he was working at a location where his job was troubling him. We love each other very much, and wanted things to work out. During this time, I felt very depressed and didn't want either of us stressing each other out. So after discussions, I decided we should take a break from each other. However, that didn't last long, as we can't really stay away from each other. During the short "break" we had from each other, I met someone online. We were just friends for a long time. However, after I opened up about my boyfriend and the troubles we were going through, during which time I was very vulnerable, he demanded that I break up with my long-time boyfriend and be happy. Obviously I felt that wasn't right because we still did/do love each other a lot. However, I just said all right to the person I met online, and said I had broken up with my boyfriend. During this time, the guy I met online pleaded and eventually started demanding me to be his girlfriend. I agreed, only because I felt bad about his situation and wanted to help him out (he had explained his own situation to me — he was very depressed and suicidal in life).
Flash forward, I have tried breaking up with the guy I met online multiple times now with no avail. I have explained to him about what is really going on and how I feel and so forth. However, every time I try to tell him the truth he becomes emotionally unstable, depressed, and suicidal. I don't know what to do. I feel horrible about this, but at the same time I don't know how to make things better. He won't give up until I become his girlfriend for sure. I love my long-time boyfriend and want to get married to him eventually, but this guy I met online, although he is nice, he just doesn't want to understand what I feel.
What should I do? I know I have made mistakes and gone the wrong direction in terms of trying to help him, however I can't even shake him off now without him making me feel guilty about it. I really need to fix this. Please help!