Is it normal that i feel so guilty killing a deer?

It should never be easy to take a life. I am saddened to hear they breed deer for the purpose of killing them. You obviously respect life and there is nothing wrong with showing your emotions. Emotions give you power, a raw power that a hardened person will never be able to tap into. This experience will help you learn to control that power. Don't feel guilty, that's a wasted emotion. I don't understand, why you think you betrayed your parents. It sounds like you are very well aware that you are responsible for your actions. You are learning valuable lessons. Good luck mon ami.