I have known about the PA since 9/14 but I certainly failed at getting them apart with the nagging and trying to force them apart but since the PA is still going on (it was an EA for the first 9 months) I don't know how hard of a stance to take now that I have backed off and quit talking about the OW and started just living a good life again.
Did you ever just flat-out tell her "I won't live in an open marriage?" What actions (not words) have you taken since 9/14 to demonstrate to her that you wouldn't?