Why do people say things about me when they don’t even talk to me

So everyone in my High School thinks I’m a bitch. And I mean everyone. But how do I fix it?

And how do they know I’m a bitch if they don’t even engage of any kind with me. If you think I’m a bitch bc I don’t talk guess what I’M SHY! Ok, I’m sorry and I mean it but if you think that and if you think “Oh I’ve only talked to her once so I’m gonna say she’s a bitch!” Guess what you really hurt me. I’m on the verge of crying and I don’t cry unless I’m really hurt. So thank you for that boost of confidence. (That was sarcasm)