I'm sorry you experienced this. I've had a severe stutter all my life and recently managed to reduce it to just a mild stammer. My first job was at McDonald's and I remember they would always put me on drive thru taking orders and 70% of the time my stutter would become unbearable and customers would often make comments or laugh It's such a terrible feeling. But I learned to not let my stutter define me. I took charge of it. If I had an interview to do, I would let them know beforehand of my stutter and tell them it does not affect my skills. Also, taking very deep breaths before speaking really helps the words come out smoother. I wish you the best!