No, it's not easy cutting off toxic friends. If you think a "last conversation" is going to turn into a screaming match, avoid it by all means. If you think you can be specific with your friend about what bothers you in your friendship - and you want to keep this friendship, which you don't sound too sure about -- then be specific and stand your ground. This is not your fault; your friend isn't there for you for whatever reasons, and yes, the alcohol is part of that. As someone else said, you might want to do an intervention... or you might just want to do a fade and not contact her any more at all. What is best for you?