You should walk up on your boss and ask "my stutter is pretty funny huh"? And watch her face drop 😂 I learned to turn my stutter in a joke , it breaks the ice and people become more accepting of it. If you feel she did this to be a real asshole then, let her know you don't like it and don't want her to make fun of it. We g2 stand up for ourselves when the situation requires it.