Dad, if your wife is using alcohol a lot and it's become a problem, part of that problem is lying and denial, not only to others but self. It's part of protecting the way a person hides from their problems instead of actually learning how to work through them. The person who develops this problem doesn't set out to develop the problem, they start drinking as a way to deaden the pain and anxiety and social discomfort as well as providing a way to feel better if depressed.

When you are thinking about how betrayed you feel, how you remember feeling this with your first wife? Well, that is how your wife felt when she caught you texting, her first marriage did not work out either. When a person is very insecure they can begin doing things to try to overcome that deep insecurity and often they can try to decide that marriage is just disappointment and that could have led to this friends with benefits venture along with using alcohol to assist in being less inhibited.

The way you are angered? That she betrayed you with sex? A woman can be just as angry even if there was no sex and "just" showing/providing companionship with someone else. The way you feel where you don't even want to look at her? That's how she felt about you only you were away and she had several months to stew in that anger and loneliness. The way you feel about "I will never marry again", well, that is probably what she felt too, and she began drinking and moved into this idea of "friends with benefits". That is an attempt to figure out how to have companionship without getting hurt and devastated.

Interesting how you both got very triggered and angry and felt deep betrayal when you got a chance to see what was meant as a private text interaction not meant for each other.

You can sit and say "yeah but what she did was worse", yet, if that is so her reaction was an indication of her extreme vulnerablity and how deeply she was affected with what she caught you doing. People who are deeply hurt do try to find a way to navigate forward to avoid "feeling" hurt. This is part of our normal human design as we are all born navigators. However, that doesn't mean the way we choose to navigate to avoid being hurt and vulnerable ends up being the best and healthiest way to actually navigate.