I am not a person who stutters, but am the parent of a child who stutters and SLP. *Anyone* mocking my child’s stutter is a hard boundary for me, especially loved ones. Siblings know they do NOT go there, I have no tolerance for it. What has happened to you is my worst fear; even at 10yrs old I have told them that someday if their significant other mocks their stutter that they should not put up with that — someone who truly loves you would *never* do that. My heart breaks for you. I hope he can understand how hurtful this was for you and never do it again, if you choose to even give him a second chance. You deserve to be loved and supported!