[notstrongenoughtostayaway]

Hey, sweetheart! I don't know how old are you, but when I was 13 I had the same problem as you. Thankfully, now I'm in high school and I have the best friend ever.
I don't think that she uses you, I'm SURE she does it. My advice is to let her breathe alone for some time. I mean that you should pretend that she is not so important to you any more. Go out with a classmate of yours and make sure that your friend knows that you are making new friendships.
And please, don't get me wrong-this is not a revenge. Just make her realise that she needs you. Make her fear of losing you.
"Then, when I was stressed, she just said, "Well then you should just stop stressing," without even asking why I was upset. I've also been called pathetic, retarded, special, stupid, etc."-that's what you wrote.
In my opinion she is not a true friend and you should let her go. There is no danger of ruining your friendship because such doesn't exist, I think. In your life many people will disappoint you. Keep your head high, don't let anybody offense you and believe in yourself!