Hi Dallying and WELCOME to SR! This is an awesome place to find support and some off-colour humour. I hope you keep coming back.
First off, let me remind you of the 3 C's of addiction, if you don't already know them:
You didn't CAUSE it
You can't CURE it
You can't CONTROL it
I think you're already coming to the realization that you aren't going to be able to control or cure your boyfriend's drinking. The only power you have is over yourself, and you're doing awesome by realizing now (before you're married, living with him, or have children) that you don't want this in your life.
I know how hard it is, but please be gentle with yourself and let go of the guilt he has placed on you. The whole "you didn't give me a chance" is bull.
Let's spin this differently: you haven't made it past 6 months in a relationship because you know what you want, you're honest, and you don't waste time on jerks (which the world is full of). My problem was the opposite: I couldn't say no to whatever jerk I happened to be seeing and ended up in loooooong painful relationships with unhealthy men.
Have you considered going to Al-Anon or counselling to get some support?
also, I would strongly suggest you get your hands on a copy of "Codependent No More" by Melodie Beattie. It's an eye-opening read...
Keep posting! SR is always here.