I'm by no means an expert, but I have a couple questions...Is the A over? I know you might not know, but does it at least seem like it's deep underground or that it might not be happening anymore? It seems that your W is reaching out to you, almost begging for some kind of communication/affirmation from you. The texts, the conversations...none of it seems mean to me. None of it seems like anger focused at you. It seems like depression and a true reaching out to you for some kind of affirmation.
I'm not saying that you need to abandon DB principles. Obviously those work. I'm not saying that you need to go full in and start talking about saving your M or reconciling...but maybe a little testing of the waters of your own is in order here. A vet can chime in better than I can, but if she's truly making an attempt to get you to open up, I think it's warranted and what is right. Now if the A is still happening and she's just playing both sides, or wants sympathy from you and OM both, then no way, but I'm a little torn with your current approach of just walking away and avoiding having potentially some game-changing conversation with her.
Again, let someone better at this affirm what I'm saying, but I've been jumping at a lot of opportunities to connect with my W because she's willing to do so. I'm staying protective of my emotions, and validating, etc., borrowing some techniques from piecing even though we aren't, but it seems to be working a little. I can always pull back if the alarm starts ringing.