Going to school makes me depressed?

My Summer is nearly over and school's about to begin, and I have a huge amount of dread in my stomach. I used to think I was genuinely depressed, until i realized the only time I felt that way was whenever I had to go to school. I've attempted suicide multiple times in the past four years, not because I wanted to die, but because it seemed like the easiest way to escape what I had a problem with. School causes anxiety, being around people makes me feel awful. I really don't like being around people. It makes me sick and makes me sweat a lot. I don't want to be driven back to feeling suicidal... and depressed, I hate it, but I feel like I'm going to feel that way whether I like it or not once I've gone back to school, I have no idea what to do. Advice?.