Okay, now that I've slept on it, GF is very right. I don't have anything to gain by making her feel confronted. She knows what she asked me and she knows why I would respond the way I did - that given the choice between waiting for her affair to end or D, I choose D. Up to now I've told her we can work on things if she's open to it, so she knows that I feel that is possible. I don't need to repeat any of this stuff unless she asks.
If she wants to do something, that's when I can tell her I need space. I just need to stop reacting to thoughts of her and what she's doing. I need to focus on what I'm doing.
I know she's confused and conflicted, but she's also really acting like this is an exit affair and there's nothing I can do about that. She has to choose our M, at least to some degree, for any of my changes to be noticed.