Wow that's awful. I think you need to confess up and tell her how you really feel. I have drinking parents, and the best thing I ever did for myself last year (im 39) is to tell them both that I am too old to put up with that shite, and to respect your holiday and time together, and if not, you cant until your mum can. Its a hard call to make, but eventually you will reap the benefits, hopefully x