Beta blockers are usually precribed for anxiety, they are great for reducing the physical symptoms of stress, i would recommend seeing your GP for a short course.
The best thing i think you can do is talk about how you are feeling to friends/family, take time to play a sport or do something that will completly distract you (if only for a few min!) so you don't dwell on it, and above all, deep breaths, you can do it, you've passed all the biggest hurdles already!