how do i get my friends to stop mocking my stutter?

how do i get my friends to stop mocking my stutter? I have a moderate to severe stutter and recently it's gotten a lot worse, whenever I talk to my friends they don't even respond, they just mock how I stuttered and they usually just interrupt me anyway. They've always made fun of it and I've usually just ignored them but its getting so frequent it makes me not want to talk anymore in conversations, and not being friends with them isn't an option because I have no other friends, I want to know how I can communicate to them to stop because when I try they don't take me serious. Sorry I've never posted to reddit before I've been really upset over this and Idk what to do