Just popping in with a question

[2thepoint]

Well, I'm thinking that some other hard conversations might have to be confronted. I feel that I need to give my wife an ultimatum: if I hear that you have brought my kids around OM or him around them, I will talk with them about what is going on from my perspective.
I hope that concern for my children is a bigger part of this than my pride.

Really need advice on this, including how to approach it.

What you describe is setting a boundary. Boundaries are good but you have to be able to enforce them. I'm not sure though how flushing the "dirty laundry" of your W's A out into open is going to help the kids. Seems like it only helps you and is a bit of a back handed slap at your W. I don't think that is how you intend it but that is how it is coming across.

There is a book titled Hold onto your N.U.T.'s. N.U.T.'s refers to your "non-negotiable unalterable terms." If you haven't read the book, you should check it out.