When I get stressed I pretty much short-circuit. I get jittery and twitchy and sometimes I develop nervous ticks. Depending on the intensity of the situation, I'll just randomly start to break down and cry, though rarely (it's only happened twice my entire life).
As far as dealing with it, sleeping is the best way to go. Either that or some kind of artistic catharsis where you can just let it all out -- playing music, cooking, or even doing a bit of feng shui. Then as I start to calm myself down about it, I can start doing something menial, yet productive like cleaning my room or organizing a binder. Once I've finished that, I can be happy that I've done something and it makes me feel better. Then I'll be able to move on to doing what I was doing originally.