You are in a tricky situation. You love your friend dearly but she is an adult. Adults make choices and you wouldn't make the one she is making (staying with an alcoholic) but it is her life. I've had friends in less than healthy relationships, some with addicts but I know I could never manipulate or do anything behind their backs in the hopes that they see what I see. They may, they may not. This is her journey in life. If it is too much for you to hear the repeated patterns of what she is putting yourself through, you have every right for yourself to put up a boundary with her. Just tell her that as much as you love her and are there for her, it is painful for you to hear about how he treats her. That is all you have to do. Then change the subject. Keep doing that every time she brings him up. But don't go to her mom with this. What she choses to tell her mom is her business.
Try not to judge her though or think you wouldn't be in that situation because you may find yourself with someone that your friends would not approve of. Then what would you do? Your worries for her are valid. Express your concerns if that will help but distancing yourself from her situation is really all that you need to do. good luck
