My fiance has been struggling a lot lately with this and it's taking a toll on me. I'm doing all I can and all I know how to do but it's getting really hard and exhausting to deal with the constant cycle of abuse and then apology and then abuse and then apology over and over and over again for months. Usually day by day. I have convinced her to go to a counselor for help and she has an appointment set and seemed willing but she has kept up the cycle of drinking and I'm afraid she'll just ignore it or pretend to go. If anyone has experience helping a loved one through overcome this I would appreciate the help. She is an absolutely wonderful person when she is sober and I love her with all my heart but I'm not sure what else I can do and I don't want the rest of my life to consist of this.
Though I've not dealt with alcoholism specifically, I've experience with very serious relationships that were 'good when they were good, but abusive when they were bad'. Relationships I stayed in for many years too many, because I loved her and I thought things could change. From my anecdotal experience, I don't think there's much you can do but tell her how her behaviour affects you, support her insofar as you're able, and hope that can inspire change.
Past that, I just want to say make sure you take care of yourself. It's a certain possibility that she will not meaningfully change. No matter how much you love a person, you should never feel obliged to put up with being abused, no matter how infrequently nor in what context. And doing so will help neither you nor her. Best of luck.