Name changed for this. Sorry if I waffle, wine effects 
I'm finding it hard to maintain my friendship with someone who had an affair. The marriage has been rocky for years, he's an alcoholic, they have one child and she is very unhappy in the marriage. She contemplated this affair for ages with a guy that she's known for a long time and was previously unfaithful with him (ons) a few years back but recently started back up with him again.
She's come clean to her husband and although he originally wanted to divorce he is now buying her expensive gifts, suggesting holidays, and doesn't seem too bothered by the affair from what she says.
My friend wants to divorce and has told him this but she won't initiate it while he is still drinking. I don't think he's ever initiated anything in his life. I don't see him ever being sober, especially now he knows she's not committed to him. Mentally she's left but keeks saying how sweet and thoughtful and generous he's being. She says she can't physically leave because of the effect on their daughter and finances.
I know it's not my problem but how do I handle the friendship when I disapprove very strongly of what she's done? I was cheated on by a long term partner and father of my dc and it was horrific.
I feel sorry for their 8 year old daughter who is caught up in what sounds like a very confusing home life as it's silent treatment, sulking, separate rooms, moods and hidden bottles of vodka in the office yet all loving and thoughtful on occasion. I grew up with an alcoholic and know how it affected me with the constant anxiety and treading on eggshells.
I know I'm probably projecting a lot here and am very sensitive to the situation because of my own experiences but I'd appreciate any words of wisdom.
I've started over the past weeks distancing myself a bit from the texts about the relationship. I know she's very unhappy, I know he's unhappy, but I can't condone her behaviour and she knows I strongly disapprove. She's no longer seeing the man she cheated with but still wants to and I don't think it would take much for her to start seeing him again.
I'm trying to be a good friend but finding it tough. What can I do?