Hey Mike. Glad to hear your update, even if it is a difficult one. At one point ~5 years ago, my W was engaging in an EA with a co-worker (whose wife was dying of cancer....so he was mad, furstrated, looking for attention, etc.). I'd caught her wishing him a happy father's day while we were with my father celebrating father's day. Talked with my IC about it who told me, in no uncertain terms, it was time to tell W that she had to choose between him or me (and mean it of course - which I was prepared to do). He was a co-worker of mine at one point. One, in fact, who I agreed to be a reference for.
W in fairly short order blurted out that she was choosing me. I told her to take her time to be sure because if ever the boundary was crossed again, I would 100% be able to call it quits. I noted that I deserve to be treated with more respect than that, even if it was only an EA.
So, much like DNJ, you'll hear no criticism for me on this. I do agree that it is better positioned as a boundary than an ultimatum or punishment of some kind. The action is for you, because that's all you can control. And, as you suggest, actions speak louder than words. So, continue balancing repair work and piece-work with some detachment or continuous investment in your own self care and well being. If you're putting in the work to be the best person YOU aspire to be, then you are a prize in any relationship and deserve to be recognized and treated as such.
Keep us posted and I wish you the best and ongoing support as needed. -P
