A year ago my girlfriend’s cousin made fun of my stutter and it bothered me so much. I explained to my GF how it hurt me and she didn’t rlly understand at first until I literally broke it down to her. Sometimes even the closest people don’t understand how bad it rlly does affect someone’s self esteem. A year later she is super protective (in a good way) about people commenting on it. And sometimes I need that voice bc I don’t have it (literally lol). So just break it down to him, fully explain. If he still doesn’t get it, cut that hoe off. You don’t deserve that.