It sounds to me like your biggest problem with her is just that she refuses to reconcile with you. Guess what, she can't do that right now.
In my estimation you can either apply pressure for her to R, which will likely drive her away because she is not ready... or decide that you can somehow make the pretend (for you) happy family thing work for a while longer. You know which plan your boys would prefer.
IC's advice is a Last Resort Technique in my opinion. Best saved until you're really sure you're done, and truly can't take the sitch any longer. The reason I say this is because there's no good way to take it back without losing credibility if it doesn't work like you had hoped it would. You're basically pulling an ultimatum on her.
"Commit to being my W or I'm cutting you off"
I can almost guarantee that's how W will see it.
What if she calls you on it? Then what? Are you ready for D?
I think you may want to make some changes that will help make things more comfortable for you to stand. SA offered some good idea's above, and I'm sure you could think of others.
Instead of "not act like married couple" maybe just pull back a wee bit... get yourself a little more space.
Tough stuff, I know. Hang in there Bro.
M: A really long time. Crisis: 5 years. She's still worth it.
Life is never made unbearable by circumstances, but only by lack of meaning and purpose. -Viktor Frankl
