I only want to say that your W will trust that you are no longer pursuing her, WHEN and ONLY WHEN she chooses to believe that.
No words are going to convince her of that. While I accept what your brother says about conveying that message to your X, I'll just expand on that by saying / repeating... It will be your continued actions of NOT pursuing your W that will eventually lead to her believing it...
So he is right, I just don't think words will make that happen... time and consistent action will... eventually...
I don't disagree with anything you've said. Fact is...I agree with everything you've said here. When he talked with her about the problems our kids are having, she told him that she harbored much resentment toward me...making communication between us about the kids hard. He felt this might alleviate some of this difficulty...however small...start things down a more healthy road, so to speak. She would benefit by knowing that I did not intend to pursue anymore, and possibly by knowing that I wished her well, and possibly by knowing that I intend to move forward in my life without her, and lastly by knowing that my ONLY concern now is for the well-being of our kids. I also think he believes that by me truly wishing her well (and meaning it), that I'll benefit from that too. And the kids will benefit too, for once, from their parents finally co-parenting and not using them as tools to hurt the other. ...with the understanding that actions speak louder than words.
"Always go straight forward, and if you meet the devil, cut him in two and go between the pieces." - William Sturgis, clipper ship captain, 1830's.