Welcome Somegirl66,
You have made a very important choice in coming here and that choice if you know it or not, is this:
You have decided to not accept it any longer. You have decided to put your house in order. You know pretty much everyone on here understands you and where your coming from when you use alcohol as an escape, I certainly do. I often used alcohol to escape my feelings if only for a few brief hours. Problem is, your joining your Sister in hurting and abusing yourself.
Your number one priority is stay sober today/tonight. Worry about tomorrow, when you wake up. Then put your energy into not drinking alcohol tomorrow.
If your anything like me, you will start to get all kinds of emotional baggage coming out. I have been told by my Therapist (yes I have one), this alcohol is very good at helping your mind suppress emotions and memories. When we stop drinking, these come to the front. Over the next few weeks, providing we stop drinking (I am 3 days stopped), our minds will rationalise the things that have happened to us and we will accept they were wrong.
It is at this point we can confront our problems instead of hiding and suppressing them.
In your case, you will have some decisions to make on your Sister and Mother.
This needs to be thought through clearly and I dont think now is the time to address these problems as they are very serious indeed. First you need to get better and we are all here for each other.