Hi Cinco...I am glad that you are tackling this very difficult but important issue with your wife.
Please - just one thing I want to point out to you after reading about the "blow up" etc - - you really must be prepared for everything to get way worse before it gets better. There may be a full-on separation before this thing is done. Once you both start working through all the issues, and the old pains and then the A's...you will see that her leaving for one night is just the tip of the iceburg.
But try very very hard not to be afraid of all of that, ok? Realize that it really will take all that pain in order to move through it all. And also, keep focused on this fact: the pain you endure to try to fix this will be NOTHING like the pain of a divorce. So no matter what it costs you, GO THROUGH IT and remain strong.
And one more thing...I know you feel really bad and you hate hurting your wife, you love her, and when she gets her feelings hurt and tries to run away, you have a tendancy to want to drop it for now so that you won't have to see her in pain. But here is what I want to say about that - - don't give in to it. I know it will hurt her, but please dont' treat her like a hurt child.
Don't treat her like she has done this to you on purpose either, of course, because she hasn't. But DO treat her like she is responsible for her half of the marriage. In her view, this may feel to her like she is being beat up...but as long as you know in your heart that you are just being honest, not beating her up, eventually she will see the truth in that and she will stop trying to run away. Once it "sinks in" to her that she cannot avoid this process without losing you, she will get on board.
Stay strong and kind and loving...but do not divert responsibility for her, ok???