A rumor has started about me

Well today my friend told me someone asked her "doesn't Cassidy have an std?". Apparently a few people have said it. I am 100% STD free, but it still ruins my spirit. I'm always happy and confident, but now I don't feel beautiful, I don't feel worthy, and I don't feel happy. My parents wanted me to move to another school because my last one was a "public school and it was so bad." Now I'm in a private school which is thought of to be "nice and friendly." But it isn't. I've never had a rumor about me start until I've gotten to this school. I feel terrible, I feel like people look down on me. You guys can call me dramatic if you want, but this literally hurts my soul and I don't know how to deal with it.