My older brother makes fun of me sometimes

My older brother makes fun of me sometimes During the few times when my stutter comes out, he makes fun of me. He imitates my stutter, and will say something like “hurry up! Your answers always take forever!”. I’ve tried several times to tell him to stop, but he doesn’t listen. Nearly two months ago now, he and I got into a really big fight because I called him out on his teasing. I tried to explain to him that his teasing only makes me more nervous socially. He then went on this ten minute long monologue about how he’s right and I’m wrong.