Here is an excerpt from my book (Building The Perfect Game) that offers advice to deal with situations such as this:
Most importantly, you need to be aware of your perfectionistic beliefs. Notice where they start, where they are leading, and where they end. When you are experiencing stress, depression, or anxiety, write down a description of the event and then record a list of your thoughts related to the event. It is my suggestion that you keep a diary or journal.
For example: You are going to play in a tournament and you are feeling anxious. The thoughts you write may be similar to the following: “What if I blow this match? I never do well. I’ll never amount to anything in pool. As a pool player, I’m just a failure. I may as well not even try. So and so always wins, I never do.” These are examples of what perfectionist thoughts do inside our head. Remember that negative thoughts breed more negative thoughts. Positive thoughts breed just as quickly.
Once you begin to examine your thoughts on a regular basis, it will be difficult to ignore the thought process that contributes to your experience of stress, depression, or anxiety. After you become aware of these thoughts, you want to examine them and determine the irrational ideas they may contain. For instance, in the above example, the individual is engaging in catastrophic thinking, all or nothing thinking, and hopelessness.
Catastrophic thinking occurs when a person thinks that the worst possible thing will happen. It can often be distinguished by “what if” questions. All or nothing thinking, common for perfectionists, is the belief that everything can be categorized as opposites--good/bad, black/white--with no shades of gray. Therefore, a person either succeeds or fails; there are no degrees of success.
All or nothing thinking can often be detected by use of the words always or never. Hopelessness is the irrational belief that the person already knows the future outcome of his or her action and has no control over future events, and therefore, need not attempt to change the situation.
Once you have determined your irrational thinking pattern, it is time to challenge and change the beliefs that add to your stress and anxiety level. This is what leads to fear, anxiety and guilt, and this is where we can put out those flames of negativity. If you have correctly identified the irrational beliefs, you can challenge them directly.
For instance, with catastrophic thinking, you can state, “The worst possible thing is not the thing likely to happen.” For all or nothing thinking, you can state, “It is not true that I always fail." For thoughts that put down your faith in yourself, you can say - "I am capable of winning. I have all of the talent and skill necessary to be successful.”
Our perfectionist thinking and patterns did not occur overnight. This flaw in our attitude will not be changed overnight. It will take a lot of practice, a lot of repitition. These positive statements must be used to counteract the negative statements. You have to tilt the scales in the favor of the positive. This means that you must be more positive than you were negative in your thinking. You must use these positive statements frequently and cosistently in order for the change to take place.
Finally, the strongest challenge to irrational beliefs is opposing experiential evidence. In other words, you want to experience making mistakes as a POSITIVE influence in your development as a player. Making mistakes gives us the opportunity to learn and to grow. As you overcome your fear of making mistakes, you will be able to take risks. The ability to take risks is what allows a person to be successful in any endeavor. Nothing risked, nothing gained. That is so true with pool and with life.
One way to experience mistakes is taking the opportunity to deliberately make them. First of all, identify situations that are fearful for you such as missing a pocket hanger, or miscueing on the break. Then, deliberately engage in the behavior while using rational self-statements to help yourself cope with the situation. One thing to remember in this process is that what one person may consider a mistake, may not bother another person. The most important thing is to face the challenges of pool by risking mistakes. In doing so, you will become more self-confident and will be able to accomplish more because your fears will not inhibit your playing or your mental attitude.
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a rattle snake bites me in the face. Clear your mind of negativity, don't shoot until you see/feel the shot, never miss. It's that simple 
