Social anxiety and high school?

last year i was in eighth grade and was having a lot of anxiety so i had missed quite a bit of school later i got the swine flue and had to be home for a week, no one believed me which was understandable but i had a lot of anxiety so because i still knew education was important switched to online school, and left with out telling anyone except 1 person who is still my friend, but other than that i really dont have a lot of friends, so this year i decided it would be better to go to a high scool, so 1 the though of just going back scares me and 2 the though of seeing this people and worrying what they will think, say, or confront me. i wanted get my schedule like a week before i start to know what i', getting into and to get over the fear of just going in but the school says they dont do that, and i do really want to go, but every time i get to close i chicken out, so i'm not sure what i should do? i'm supposed to go tomorrow but i'm really scared to be in cles with a ton of people i dont know or know i reall dont want to see again, BUT i just dont know how to push my self to do or how to be confident or... not terrified. any advice would be appreciated