Hi HS, and
to SR! Wow, you could have written my story. Or I could have written yours. My sister is an alcoholic, too. She is currently in a program learning how to recover. I have limited contact with her, on my terms. But it took years of pain, frustration, and education to get to this point on both our points.
Of course you love your sister, and of course you want to support her if she chooses recovery. IF she does. At this point, she hasn't, and it sounds like you are ready to do what is best for you, which is to set boundaries that protect you and your family from being dragged down into HER choices and HER spiral of madness that is alcoholism.
Boundaries are not selfish; boundaries are there to protect you and to set up consequences for the alcoholic and his/her behavior. But...they only work if you set them and you stick with them! I know how difficult it is because you do love her. My alcoholic sister was / is very good at manipulating and playing on her loved ones' emotions so she could continue her behavior. I had to set boundaries for my sake, not for hers, as harsh as that sounds.
Your sister will make the choice to get sober if/when she is ready to, and you can support her then. But in the meantime, detaching with love may be the best thing for both of you.
I have found I need to reinforce my boundaries with both my sister and my parents (who, like your parents, want to pretend everything is "normal") regardless of how either party feels about me reinforcing my boundaries. I do it in a neutral and loving way, and I stick to it. I don't accept hysterics, drama, or criticism. If we cannot communicate like adults (I am speaking here mostly about my parents, though this applies to my sister, too), I do not communicate with them, but leave the channel open with "when you are okay with discussing this in a rational and calm manner, you can give me a call".
I know it is so hard...hang in there and keep posting! You are doing the right thing. On this forum, I learned that "if nothing changes, nothing changes". If we don't change...the alcoholic won't either. But regardless of if / when they change, we can live happier days.