Hi JC, it sounds like the affair you had was resolved between the two of you and that things were fine afterwards. You both even said "better than ever". So I think she's using that as an excuse now for her wayward behavior. Don't buy into it.
You've done a lot of things right already it sounds like. You've read DR, you have a DB coach, you're giving her time and space. That's all great. Don't pursue her AT ALL. Leave her be. This affair of hers will fizzle out and she'll have to face why she went down this road. If you effectively remove yourself from the picture then she will hopefully face down her own demons and quit blaming you for everything. But that is HER journey to make and you can't speed it up, you can only get out of the way. If you try to intervene you are just going to slow her journey down. So leave her be. Get out and GAL. Be the best "you" that you can be. Be patient, these things take a long time to resolve!