Hi Boxerchick,
I'm so sorry to hear the pain you're in right now. Break ups are hard , and it really sounds like your confidence has taken a bashing, and your world has turned upside down. And now you're starting to wonder if you could have done things differently.
But from what you've written, it sounds like you've done everything right. It sounds like you were setting boundaries. Making it clear that you didn't want to be in a relationship with an alcoholic. I assume that's what the complaints and arguments were about.
When you've had a chance to read some of the stories on here, you'll begin to see that, as others have said, your boyfriend has done you a favour. He doesn't want someone setting boundaries for him. He wants someone to make his drinking as easy as possible. You'll see terms like "enabling" and "codependent" a lot. That's the kind of girlfriend he wants right now. You say you feel worthless right now, but I would say that you've shown how strong you are, standing up for your beliefs. Good for you. You deserve someone who will respect that, and value you for it.
I hope some day your boyfriend will realise what he's already lost through drinking and will choose sobriety, but you have no control over that, sadly, and it could be many, many years, if ever, before he chooses to do that.