When a guy mocks you its ok because you can punch him but when a girl says that it kinda shatters your ego. I went through my school days mostly quite because of this. The best thing to do is to let it motivate you to improve your speech whatever way you can. Read books, therapy, talk with people you stutter less etc. Fuck those people who mock you. To that girl I would say "I might stutter but at least im not a hoe", then leave. Just focus of yourself bro, get smart and rich and in the end people won't give a shit if you stutter because you got money and power. So you can be an ass to them.