Hi , I know it's hard and you're already feeling really bad about it. It's okay don't be hard on yourself. The more you think about it , the more you'll get stressed. Try distracting yourself in other good things. I would recommend that please don't think much negatively about it , what if you ace it? And do it smoothly? You can try meditation and a little bit of speech exercises before your day. You can even practice what you want to say. And you can invite your close friends or family members with whom you think you will be comfortable while delivering the speech. relax your mind , declutter your thoughts. You're going to deliver an amazing speech.. good luck! ✌🏻