Re: Dealing with sudden fear
David's links and Adams' post should be taken deeply into consideration. FEW martial arts programs work on severe stress inoculation. Adam points out that the military knows that the best way to address this issue is to incorporate severe stress inoculation training as part of their regular training paradigms. Even then, there is always a percentage of people who, with that training, will still become overwhelmed by the physiological results of stress on the body. Someone I use to train with referred to that moment of realization as "the moment of pooping or playing." Heroes are people who experience fear like everyone else. How they reacted in those moments became the defining factors for the label that was later put on them.
There is plenty of information out there on how to condition the body to best handle severe, sudden stress. If you are seriously interested in exploring that area, that is best done as a separate component of training that can incorporated into your martial arts training as well.