Your issues are very familiar to me. The hardest mental challenge of competing is exactly what you are struggling with. It's okay to be results driven and oriented, but if it affects how you feel about yourself and your life there is a problem. I went through this exact problem playing another sport. When I performed poorly, which became frequent, and I was being beaten by others I felt should not beat me and when I was continually making "stupid" mistakes that caused poor results I let it affect how I felt about myself and it would ruin my state of mind for days at a time.
This is exactly why I quit the other sport and decided to finally try organized shooting. I am now much more interested in the shooting process and enjoy both tanking stages and running them well. I am still driven by results, but I am 100% content and accepting of sub-par performances. The results do not affect my outlook on myself and my life. This is why shooting has been good for me.
You have to realize when you truly have the capability to perform consistently at a high level and under pressure it will come out. Until that happens you are not there and cannot expect it to happen. I promise you will get there easier if you relax, turn it loose, and allow yourself to be content with the outcome before it happens, whether that is a stage/match win or a zero.
I hope my ability to be accepting of competitive shooting outcomes can transfer into other arenas of my life where I strive for results. Not only does it enhance performance, but it allows me to be content as a person.
If you can't do this with shooting, take a break, experiment somewhere else. Things may change and you may gain a new perspective that will help in the future. At least, this is my personal experience.