I have to say that you will ALWAYS hurt the One You Love, i Know how it Feels my Bf right Now is a MAJOR Drug addict and no matter what i do He getan hurt. The Best Thing to do is to always Tell them you Love them.
I agree with ~Atlantech, you need to figure out what is making you feel this way, whether your frustrations are because of him or because of something else, but you can only do that if you are really honest with yourself.
It is quite possible that you are pushing him away because of an entire separate external issue that is bothering you, or it could be something with him or your relationship that is bothering you but are trying to pretend isn't an issue because you're afraid of losing the relationship, which is why when you try to see what is really bothering you, you need to be really honest with yourself, even if the answer isn't one that you like.
first of all, you need to identify your primary emotion, and then second, you need to identify whatever it is that is causing you to feel this way. When you can take a step back and see what is going on inside of your head, you will get a better understanding of why you are pushing your boyfriend away.
Take some time apart and maybe think about seeing a psychiatrist. Perhaps you are having episodes due to chemical imbalances in your brain.