You need to tell her, and you need to stop. Detox is awful, the sweats, the fear, the shakes etc, but, it's not that bad. We have all been through it. Unless you tell her that you need to stop, and that drink is now going to put your life and your relationship in danger, she will continue to bring drink into the house, and you will drink it too. If you want to be fair to your GF and fair to yourself, you need to sit her down and be honest.