GalaGirl and WhatHappened, thank you for your replies.
I know it sounds messy, I guess details have a way of being that way. I'd like to take your advice, but its very hard to let a good friend go. I honestly have no other friends with whom I have been so close. We have had conversations about all of the points you raised and she acknowledges their wisdom. She has come out as poly to her family, which is more than I've been able to do, and she did attempt to renegotiate the communication agreement, but failed. My wife and I had been working on this for years, I can't expect her to make the same progress overnight. If we measure our ethics by what makes us feel least yucky, well... I would prefer to remain a messy and imperfect friend than cause us both to loose a friendship on principle.
38 M, Straight, Minneapolis. “Love is that condition in which the happiness of another person is essential to your own.” -Robert A. Heinlein, Stranger in a Strange Land