You are a good man doing your best in a really really hard place. But what you are doing is not working -right?
So my ideas are: STOP - stop trying to save your marriage, stop trying to fix your wife, stop trying to figure out if you want to be married to W. Its all out of your control.
So what can you do instead?
The words are 'lovingly detach'.
What does that mean? - Firstly you do this because you love yourself, your wife and your kids. You dont do this because you want to 'pay back' or 'teach a lesson'. Detach - meaning to separate yourself from W's anger, drama, tension, upset. You can do this while physically being present (and I agree with your thoughts that you should not be the one to leave at this stage). Detach - withdraw so that you can reserve yourself, so that you can still be true to yourself and be OK. Find your inner mojo!
I know its hard but it will help you a millions times to be happier and more in control of yourself. You dont want to be swayed any longer about what W is thinking or doing. You want to be centered.
Replace all that time and energy that is currently going into worrying about how you are going to fix this mess, you should instead concentrate on you. I know in the start I had to break it up into blocks of 30 minutes. A 30 minute break where I did something I enjoyed.
You know what is really crazy? You are SO great, and W is the one missing out on you - not the other way around. You cant fix her but you can fix yourself so that you can draw her back to being attracted to you.
