I can assure you that MOST people will grow out of this behavior as you get older. I haven't had anyone say something that rude to me about stuttering once I graduated high school. Kids are NOT very understanding of others, due to their immaturity and their lack of real life experience. People like her ARE everywhere when you're young and in school, and it really freaking sucks. Sure, I will have some adults make an off-hand comment about my stutter at times, but it's rare compared to those days in school. When you're older, you also have more of a personal authority to tell these people to fuck off, because you aren't normally stuck with them everyday. You don't have to take her shit - you have every right to say something to her, but don't expect her to understand, apologize, or change her behavior. You can tell her how you feel, but be prepared to deal with her not understanding where you're coming from, which can be frustrating, but expected of someone that age/maturity level. I know this might not help you much right at this moment, but I hope having some foresight into the situation may soothe your anxiety. A person like this girl is so frustrating to deal with, and I'm sorry you're going through that.