There was a word you used that jumped out to me that said you did not need to go there to try to be her "knight" was when you said.....disgust. If that describes your W's feelings toward you, then I say you need to stay as far away from her as you possibly can. Disgust is not a good thing for a woman to feel about her H. That means she is very, very turned off by ANYTHING he does. So save your self-respect and not go there in August b/c whatever you do to interfer......I think it would only result in her pressing closer to the OM. Perhaps the men see it differently, but that is how I'm seeing it from the W's POV. When you used that adjective to describe her.....that told me all I needed to know.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!