Hello Shorty and welcome
AA meetings for her. As she learns the steps, she will also learn how to deal with the pain in her past. Can't force her to go. Can make the sugestion for it though. Al Anon for you and your sister. Al Anon will help you understand things a lot better and help you deal with any emotions or guilt you may come across.
You shouldn't feel guilty or ever think it is your fault or anything like that but feelings do arise as we all are affected when a family member drinks.
Look about. See what the Al Anon board has and know you are not alone.
Seems you have a great understanding on things already. Your mom is blessed with daughters like you.