Welcome.
When a partner threatens to leave us over alcohol, the partner means it. Your gf appears to be an alcoholic and completely in love with drinking.
It's very unlikely she will "stop cold turkey" and that "everything will go back to normal." (It sounds as if it has never been normal really).
Alcohol loosens inhibitions. So if you stay with her, prepare yourself for some shocking behavior. And possible infidelity. Alcoholics do not keep promises, about anything. And when they break their promises, they are very skilled at covering it up and making their partner feel/look crazy.
Good luck. Read the Sticky links on the opening page and you'll know more about the rollercoaster.
Just don't sacrifice your values and standards to her addiction. You'd be amazed how much we minimize being abused by our alcoholic partners.