I agree. I also think most fear, stress, anxiety, call it what you want -is delusional because chances are your not being chased down by a lion fighting for your life. It comes down to coping skills and im sure there are a few simple things people can do to calm down some better than others. Some people, smoke, drink, eat, think positive thoughts, visualize, hum songs, etc etc.
My advice to the op is to find out what your afraid of and work on that. Losing, missing balls, being dissappointed in yourself, expecting more from your self, people judging your game, etc, etc, are all part of pool. If you can learn to surrender and accept these things, it may help with your nervousness. Good luck.