As often as she harpes on old hurts, have you ever asked her what she wants YOU to do? If she keeps bringing it up, she's clearly still angry about it. She couldn't even kiss you goodnight after having that talk again.
I believe she is either hanging on to unforgiveness to justify her A.....or she feels these issues were never resolved and is needing SOMETHING (from you?) to help her put it to rest.
I really can't see the M reconciling until she finds peace with this. If there is something she expects from you.....find out what it is! Otherwise, why do you put up with this same old stuff over & over? It needs to be resolved or stopped once and for all.
I can tell you from experience that the more you allow her to browbeat about the same past offenses, the more unattractive you will be to her. B/c she is keeping that old wound raw by aggravating it all the time. In doing so, I believe it affects her level of respect for you. So I am saying that there comes a time that just listening to her harp is not healthy. You've tried validating her when she does this, right? It doesn't seem to stop her from bringing it up again.
So once you write a letter giving her a pound of your flesh, what is left for you to do? Didn't you try apologizing for everything quite some time ago? She wants you to continue apologizing over & over for past offenses, but she can't apologize for being unfaithful and for not being willing to disclose her whereabouts?
P.S. Regarding you thinking she didn't meet OM b/c she appeared too relaxed and happy, instead of being anxious. If a drug addict has just had their "fix" how do they respond to it? How does that differ from when they are needing a fix really badly? Think about it.
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!