answer:Immediately? Take at least 10 deep, long breaths. Count to four while you’re breathing in, and then again while breathing out. The counting takes your mind off the other stuff, and the breathing helps your nervous system calm down. Find something that helps you calm down right then. Maybe it’s a bath, maybe it’s a quick game of phone solitaire, or a good feel-good book (I go with Harry Potter 1 or 3). Long term? Find a good therapist who specializes in panic disorders or trauma. They can help you figure out how best to deal with this fear in ways the internet can’t.