My boyfriend mocked my stutter during an argument

My boyfriend mocked my stutter during an argument Me and my boyfriend got into a heated argument. I am a covert stutterer for all my life and have blocks where i quickly repeat the first letter of the word. During this argument I became very stressed and agitated which brought out my stutter a bit. He mocked me and said D-d-d-d-doing when I tried to get the word out. I’ve never felt so hurt. Ever. Anything else during that argument said was minimal compared to being mocked. I don’t even know if he realized how much that affected me. Has anyone had this happen to them? I am so upset i’ve been crying all night.