I know the feeling well @outlander. If it was me sitting in your place, I would be shaking and twitching, unable to stop the tears (which is not crying it's just a physical reaction with me) and the inevitable runny nose; of which fear grasps me in such a way I can not even bring myself to wipe it!
The reason I choose to think about my breathing is to change my focus. It helps 'pull in' the run-away emotions. No matter how embarrassed your feeling, or how embarrassing you appear to others, you are trying. It's like your facing a mountain so high you can't even see the peak. But keep putting one foot after the other, however you can, and not only will you see it, you'll reach it and plant your flag.
I know how difficult this is for you, how exhausting it is, how much effort your giving.
Don't give up, your stronger than you can see right now. I believe in you 