Find yourself a comfortable place, stay there, maybe with a book to get things off your mind, focus on the good things, get cozy and try to sleep, eat something, do anything to get your mind off it but if you start to hyperventilate then calm your breathing, remind yourself of good things to steady the breathing. I'm sorry I could only get to you 15 hours late, but, I still made an attempt :')
If you ever need something, I'm always here for anyone that needs it :)