If I didnt know better I would think I am your wife. Same exact situation. I did cheat. He doesnt know that, but he knows about the texts and the FB. I am not proud of it. In fact I am disgusted with myself. I just thought I would share with you my feelings so that maybe you can understand hers. Not that it in any way excuses me from my horrible choices, but there is a progression that took place. It wasnt a conscious overnight decision. Basically, I went for years and years not feeling loved at all. His way of showing it wasn't even something that equalled love to me. The yelling and the anger begin to break a person. I was, and still am, convinced that I must simply be unloveable. It hurts.....terribly. You speak of her betraying your trust. What you dont see is that she has been unable to trust you for years. She has been utterly alone. The one person she is supposed to be able to depend on turns on her regularly. She sees the pattern, it hasnt changed even when she did get the courage to brave your reaction and beg you to change. You ignored her again.....If you just ignore it....it will all go away right? You can pretend its peachy. But your avoidance just proves to her that shes isnt worth it in your eyes.
Desperate she reaches out to someone, probably a few people, to help her understand. To cope. She finds someone willing to listen. Really listen. Wow. It feels nice to have someone care. An she cares too. She understands what they are going through as well and sincerely want to help each other. But as you begin sharing confidences the feelings for each other grow. Until one day you realize its love. What a conflicting emotion. It has been so long since anyone showed love for you. Yet you know its not right. But barriers break. Desire to be loved can be all consuming. I think our spirits require love as our bodies require water. Thirst is a powerful motivator.
That said, I want to clarify that I dont condone or any way blame you for her actions. She alone is responsible for those and will have her own repentance to seek. She can not be happy right now. Poor choices never bring happiness. Just for a second, try to understand how devistated she must feel as the now this one turned on her too. Is she loveable? Was she just being used? She is probably struggling with her own sense of worth and value. Not only for the things she has done but how she has been treated. She needs time to work on herself just as much as you do. Recognize, however, that both of your spirits have been literally wounded . How would you treat the other if it were a literal, bleeding, painful wound? Would you be resentful and angry? Would you baby each other? Would you intently listen to a "Dr" to help guide you in nuturing the healing process? Some wounds are deep. Some wounds are very painful. Some take a very long time to heal. But they do heal faster and leave less of a scar if they are attended to properly. There will be scars. I know that. But like the jagged one running down my knee, scars arent painful, they are simply memories. And often (my Dr told me this) the place the was injured becomes infinitely stronger.
Whatever the path your marriage takes, my hope is that both of you acheive (notice this is an action word, it takes work) healing and peace.
Wish me luck on my journey. Im in the rollercoaster right behind you.