I read this last night, started to respond a few times, and then thought it best to not say anything. Until now.
I agree with what everyone else is saying here. I also believe I've been in a very similar spot in my life, and Im grateful to have survived it and grown from it. The girl you describe sounds just about identical to my first girlfriend in sobriety, 30 years ago. Right down to the teeth grinding. Only thing different was that she didn't drink. I spent 2 years in hell with her, romanticising things, and believing they would change. And believing that I would fix her. She eventually wound up falling in with a biker gang, and marrying a guy she was continually cheating on me with. Thankfully, I had an incredibly powerful support system in place, AA, a sponsor, therapy, group therapy, ACOA, CODA, and strong belief in a HP. It took that box full of tools to help me grow from my experience, and even with that... I repeated my mistakes a couple of times after. Found very similar qualities in the next girlfriend, and the next, but eventually the pennies began to drop, and I started learning and growing. I'm now happily married and with the same awesome, honest, trustworth, loving and intelliegient woman for 17 years. And she's hot, too
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Looking back on it all I realize I didn't really start to change, until I started making decisions that were really hard, and really cut across the grain of what I wanted to do. I started to walk away from the things that attracted me, the things that others told me were unhealthy, and lo and behold, those things started to become unattractive to me. Rather than pull me closer to new people I met, they began to repel and put me off. That was something that came totally unexpected to me. What I guess I'm trying to say is that when I somehow mustered up the strength to listen to people who knew better than me, and do things that felt uncomfortable and wrong (to me), I began to get happier in my relationships.
She has to fix herself. As long as you believe you're going to fix her, as romantic, loving, self sacrificing, and beautiful as that sounds - you're headed down a dead end street.
Last note here from me is that you are going to do whatever you feel most compelled to do, regardless of what anyone here is telling you. Most people stay in unhealthy relationships until they absolutely can't bear it any more, or they're forced out of it and the choice is no longer theirs. If you choose that road, cut yourself some slack. You won't be the first to have done that. I'd just advise you to really do your best to absorb what people are saying here, and digest it, because it's truth born of lots and lots and lots of experience. Smart people learn from their own mistakes, really smart people learn from the mistakes of others. Wish the both of you the best.