When I'm anxious, I meditate. When I'm REALLY anxious, I practice meditation for the rest of us: I put on the TV or a video game or something. Any time an anxious thought pops into my mind I think, Not Now. The feelings of tension I focus on as if they were any other physical feeling, like a sprained ankle. I breathe and just focus on any other thing.
It's not just that things are fine in the moment... it's also that all of your risk assessment is totally unreliable right now because you are wired on stress hormones.
Treat yourself the way you would if someone slipped drugs into your soda. There's no use trying to think about anything important right now, because you're not in the right state of mind. Put on a funny movie or something else mindless and just wait it out.
(In the same vein: if you can't sleep, don't stress about it. Worse case scenario, you're a little tired tomorrow. No big deal. Way easier to deal with than a hangover. If sleep isn't coming, don't push it).