What am I supposed to do?

Depending on how old you are, you should consider leaving your aunt. I think that is for the best of it. Not totally cut the contact, but keep a distance to show your aunt that you feel bad about the things she does. About the people talking bad about you, you should just ignore them. I'm sure you know yourself better than they do. It's just them acting immature. But there is always someone there knowing better. and if you are sick all the time, maybe you should consider why? are you depressed? bad hygiene? If its depression there's people to talk to. People who knows better. Now I don't know if you know your parents or anything. But they are an example of people to talk to. Otherwise a teacher may be a better help than you think. Consider what's keeping you from school, and go talk to someone about your problems. Just let it all out. and when everything is in order, you just have to gather the courage needed to carry on. and I'm sure you have it all!