Gently, are you suspicious or in denial?
My reading of your threads is that the consensus is to do the 180, but that advice doesn't seem to have taken. How come? What's keeping you from demanding transparency, etc., and kicking her out if she won't comply? (That's not meant as an attack. Rather, I assume you're resisting for a good reason - but there's probably a good way to go 180 while achieving your other goals.)
There's a big difference between being broken and being broken up.
You're broken up - overwhelmed by fear, anger, and grief. Your W is broken - she thinks it's OK to cheat.
cw, It's not fair, but nothing will change unless you change it.
IMO, your first step is to see a lawyer to determine your rights and responsibilities, and to figure out the tactics you need to employ to prevent your W from kidnapping your kids, if worse comes to worse.
Your 2nd step is to decide if your W's secrecy is a deal killer or not. If it is - and IMO it should be - you've got to figure out how, when, and where to make your stand. An MC session seems like a good idea to me, since your MC can help you both understand what's going on.
Gently, your M is over. Your W killed it. It sounds like she doesn't want to rebuild; rather, she wants a meal ticket. Even if you've let her run things in your M up to now, you can change the arrangement anytime by simply stopping what you've been doing. She may not agree to a new M, but she can't make you do anything - if you protect yourself.
Consult with a lawyer - tell him or her that you want to make sure your W can't kidnap your kids and that you may want to S/D, depending on how she responds to your requirement for transparency, honesty, NC, IC, MC, etc. from your W.
I know this is easier said than done. I know it's very difficult. If you can think of another way to change your sitch, go for it.