Your "friends" don't understand, and that's why they make fun. It's ignorance at it's worst, and they aren't doing anything to help you.
I agree with the other posters that say you need to new friends. Because you do. REAL friends don't make fun - they try to help you through your darkest times.
You need to realize for yourself that YOU matter. Not them, what they think or why they make fun. You need to decide that you matter in this world. Don't put so much stock in what these people say and wonder why they won't fight for you. If they haven't now, they never will. You need REAL support. I hope you find it.