I feel like you have done everything humanly possible to make this as positive as it could be for your W and your kids. You have now come up to the realization that your W is incapable of working with you in this space. I think you're now taking the absolutely appropriate actions to protect yourself, your children, and quite frankly your W who seems to be going off the deep end. If she ever comes out of this fog she will be deeply ashamed for her behavior through all of this.
What is best for your kids? HAVING AN ACTIVE FATHER IN THEIR LIVES. Especially your son. There is so, so much data on this. It is NOT in their best interest for you to roll over and cave to their mom. It might feel easier on them in the short term, but it won't be in the long term. These are two little humans who you are responsible to raise and turn into kind and productive adults. I don't GAF how mad their mom is going to be and neither should you. You owe it to THEM to stand up for your parental rights and if anger helps you fuel that ship, I think it is OK. It is not a selfish anger. It is a just and terrible momma bear anger and you have it and you use it to help propel you to do the right thing.
To just push back a tiny bit on what IW says above... you aren't involving your kids in this. Your W is, by limiting your interactions with them. You are being the rock by protecting them and standing up for their rights to have both parents 50/50. Yes, it wouldn't be healthy to scream vitriol at your W in front of the kids, or let them see your anger. It is OK to let that anger be the fuel that lets to do difficult things. MLK Jr had a lot of anger. Of course he did. How could he not? His genius is that he channeled it into positive and productive actions and words and changed the world.
And once this is all done? Yes, forgive your W and love as hard as you can on your kids because they'll need it. That anger will no longer serve its purpose and you can let it go. But maybe you need it right now and that is okay.
Me (46) H (42) M:14 T:18, D9 & D11 4/19 - 12/19: series of escalating BDs 9/20 - present: R and piecing