Read up on DB's author Michelle Weiner Davis regarding Walk Away Wife (or as we say it here, Walk Away Spouse; because the symptoms appear somewhat genderless in many cases).
It's like when you plant the corn, and for a week or two, you see nothing until finally you see a sprout and things start to happen that we can see without digging... Some use bamboo as that example in both directions, WAS and then also in reconciliation...
On the surface your W may have been business as usual with you for the past few years... but under the surface, she may have been planning her exit strategy, having already decided to move on.
But often we seem to notice, that if something happens to actually bring that to the surface before they are ready... there is a complete meltdown of the WAS and they go into fight and flight mode...
You indicate that you'd already checked out for a while... so it is very likely that you would have not noticed that change in her... at least not easily or obviously...
You will go through all the emotions and questions that we all go through. You'll be angry, sad, frustrated, confused... etc, etc...
So remember, this is normal...
And what we do here... the tools of DB and DR... is to help US... those who are left behind or those who would like to consider our options and possibly save the M...
The tools help us to regain our composure, let go of the emotional attachment of something that was probably not good... work on ourselves to become better people and grow through this in positive ways...
and IF... IF, IF, IF (and yes, hopefully... hope is an OK thing) the M gets saved in the process... then great...
But no matter what, you will be better... "it" will get better (what you feel, right now)... and the future will bring what it brings...
What are some of the things that your W may have complained about you, now or before?
What are some things that you think helped contribute to the breakdown of the M? We all share that responsibility and I know you mentioned some things above, but what are some of the specifics?
How can you work on those things listed above by your W and by you, that are valid and that you believe should be better in you?