Friend said that I’m stuttering and my world fell

Friend said that I’m stuttering and my world fell I have a midterm exam tomorrow where we should tell monologues in Korean. This teacher never gives me an A. I keep getting C's. I was so frustrated as I had done everything to get a good mark because I know I have a better level. I asked my different native teachers to edit my texts, asked the girl with a higher level in my group. No result. So today after my lesson was over and we were talking with friends about how nervous we are about it. And my friend didn't remember that I got C last time so when she recalled it, she said: oh it's because you stutter. I wanna die inside. She kept repeating it, I tried to be nonchalant. While we were walking the corridor I think everyone got that. My friend didn't do it on purpose, I guess she thought I'm okay with it and it's nothing to be embarrassed about. But I am so embarrassed. Only time I hate myself is when I realise I stutter. I had tried different remedies, nothing helps. Plus my depression doesn't make it better. Anyway i took a long path to be confident and not scared. I got much better with my stuttering. But after that everything just dropped. I don't even know what I want at this point. Do I want to regain my confidence or do I want to forget my problem? I felt so sick that I cancelled my plans. Every time I ask myself: why me. My speech was okay then why me. I don't endure these God's challenges