I'm not sure if you like pizza, but if you like it as much as I do, think of someone bringing a hot fresh new york style pie and sitting it on the counter in front of you, you haven't eaten all day, and think of how much you want to grab a slice...or every slice. Now think about a time you had a six pack of beer or a bottle of wine in your fridge. Did you ever sit there and get anxious knowing that alcohol is there in your fridge and you're not drinking it? My ex did. She admitted to me it actually bothered her to know that she had alcohol available nearby and she wasn't drinking it. She basically had to try and fight the urge to be drinking it. Your ex may be the same.
Granted, there are different levels to this. My ex has been on her own for over a year know and holding down a job and a life so she obviously has found a way to function somehow, and that can't mean a steady flow of alcohol, though when you start to monitor or try and put limitations on their drinking, they typically want it even more and resent you even more for trying to upset that access to the booze. It's hard not to take it personally I realize. But that's where the fight comes from.
When some kids get into their later teenage years, they tend to rebel against their parents...stay out late, experiment with booze and drugs, defy authority, basically, they start to get selfish. It's not because they hate their parents, it's just that they are becoming adults and feeling the right to make the choices and do whatever they want to do. Unfortunately, alcoholism has a similar effect though it knows no age. So it's not that your girl doesn't love you, it's just that she loves herself and her alcohol more, which causes the lashing out.
The other thing I had to realize (and this took a LONG time) is that even if she cut back, or quit, or changed anything about her drinking, because I asked her to (doing it for me, not for her) it was either a lie or short-lived. Promises or changes made regarding drinking because of a threat or because of what YOU want are promises made on very thin ice. So I realized that she needed to want to stop drinking for herself (for her health, because she was tired of the hangovers, or the weight gain, or the depression, etc...) or it would never work.
She wasn't reaching that point so I had to bail. It was not easy because I realized it meant saying goodbye to her if she wasn't planning to stop, but when I "played the tape forward" as many recovering alcoholics do, the fear of a life lived worrying about her behavior and her alcohol abuse was scarier to me than a life lived without her.