Caught in limbo

I am coming to relaize there is not much more I can to save this marriage. She is unhappy with her life. 17 years of marriage and it appears to be going down the drain. She will not talk to me. What I just don't understand is that if she is so unhappy why wouldn't she say anything even when I open the door and express my frustrations. If my CS can share her frustrations with her "just friend" guy why not me? I know the standard answer from her is because of my reaction either just by body language or by my own defensive answers. It just seems as though she wants me to dismiss the infidelity and move on. I don't need to know why she did what see did. How can a person just give up on 17 years of marriage and 22 years of being a couple? This is just me venting knowing that CS's are focused on their own self serving motives but at some point I hope just a glimmer of empathy will be voiced from her. When I ask her if she thinks about what the betrayal she says not a day goes by that she doesn't regret what she did but finding the true reason why escapes her. For now I must be content with the fact that she is soul searching and hopes to find the answers. So in the meantime I am caught in limbo expected to wait it out while she figues herself out.
I know I may never know and this is a question posed by nearly all BS. I know the stanard answers as to why she chose to betray. Selfishness and the ability to compartmentalize but I just don't get how a person could continue living life in a way so toxic to themselves and everyone around them. I am unhappy too but to just give up is beyond me.
Now I must breath and be a better man for our family.