I'm going to try to go line by line here and detangle this.
I hope your beliefs are wrong there.
Why?
If my wife withholds her blessing to reform the relationship, the odds of a refusal from "my AP" rocket even higher. Objectively, the smart play by me would be: I should commit purely to my wife, mine for alternative friendships wherever I have a chance, & live a long & blissful life, gracefully freeing "my AP" to live her own life without me on her own continent.
Yes. Now say that again but a little more straightforwardly, with less dramatic flair (or possibly sarcasm?) Objectively the best thing you could do would be to commit yourself fully, heart and mind, back to your wife and marriage, get your need for social interaction met by people with whom you haven't historically fallen in love, and let OW go.
Maybe it would be of some comfort to you to turn back to your faith. You talk about the grief and anxiety you feel thinking about her moving through the world, not knowing whether she's okay or what she's going through, not knowing her joys or sorrows... But is she not also God's child? Do you doubt that our Heavenly Father has a Divine Plan for her? Lift that anxiety up to Him, so that it may burden you less, and see what He does with it... I do this quite often, and while sometimes I get unexpected answers, He always hears me and takes care of me. The Book of Psalms contains something like 65 psalms of lament, which I think my pastor calculated to be like 40% of the psalms, IIRC. God endorses lamentation!
The pain of loss that you describe as transient? It hits me sometimes uninvited, but you should understand that I literally call-up the pain of "my AP's" absence every night as I drift off to sleep as a kind of twisted security blanket. Long after my wife has gone to sleep each night, I cry myself quietly to sleep thinking of "my AP" and hugging the pain like a pillow. It's been 5+ months. And I literally searched tonight for tips on how to hang onto that pain. No, I am not a masochist. I just simply still love my former friend. (I get it: that doesn't sound amiable; it is, though.) The pain of her absence isn't at all a "good" feeling, but it's the closest thing to tangible I have left toward her after having been made to delete my old Discord chats with her, etc.. In that sense, it's pathetically comforting to me to have at least the pain. So... supporting and comforting as I'm sure you meant to be by your assurance of the pain of loss tapering terminally, the notion of losing that pain is actually terror-inducing.
Do you think you might be stuck in a mutually reinforcing cycle where having to go NC has caused you grief, pain, and loss... But if you hold on to the hope that you might someday get OW back, then you don't have to accept the loss... And then because you don't accept the loss, you decide to cling to the grief and the pain, so that you don't forget her... But of course that keeps you stuck with the feelings of grief, pain, and unprocessed loss, still...and you reason that the only thing that will stop the grief and the pain is getting OW back... So you cling to the hope... round and round you go.
The place you interrupt that cycle, if you agree it exists, is the refusal to accept and process the loss. Like I said, you don’t have to forget her or rewrite the story so that she's a villain. You can lie in bed at night and think, "The relationship with this person was wonderful. I miss her. It hurts that she's gone from my life... But, she isn't coming back, and that's for the best." That would be consciously deciding to move out of the denial and bargaining phases of grief and into acceptance.
My plan is still to spend the next 19 months completely all-in on rebuilding my marriage.
You say "completely all-in" but you very much are 99% out, making the marriage, your fidelity, and even the continuation of your life contingent upon whether you are "permitted" by your BW to resume contact with OW. You also reject the idea that your wife should be granted full knowledge on the conditions under which she is making decisions about and participating in the marriage. Imagine if somebody profoundly hurt you, and you spend two years healing, trying to forgive them, rebuilding trust and remaining in the relationship with them, only to find out that the entire time they were still planning on doing something hurtful again two years later? Would you not feel doubly betrayed, and disgusted by how they wasted two years of your life, because they couldn't just be decent and forthcoming? That's the furthest thing from "transparency." That's lying by omission and manipulation.
However, if "my AP" rejects the overture (as I suspect she will do, absent a blessing from my wife), I'll respect that "no" immediately, cleanly, and for all time.
It also strikes me as odd that you can so readily accept OW's agency if she declines to resume the friendship, but you don't grant the same acceptance of agency to your wife if she doesn't want OW in your lives.
I suspect you meant that observation as wry humor (we are, after all, absurdly simple), but I want to pause momentarily to recognize that I detect both authenticity and pain in that clause. I'm sorry you're still hurting.
Here's the thing. Being sexually and romantically rejected in adolescence made me somewhat of a "hoarder of men" and sexual partners as a young adult, and the multiple instances where I chose infidelity are probably the biggest regrets of all 30 years of my life. At the same time, without the infidelity recovery process, I don't think I would have ever been motivated to examine that mechanism and address what was broken inside me... And now, while I can look back and recall the pain and the desperation I felt back then, I don't actively feel it anymore. I'm the happiest and most whole I've ever been in my life right now. That's the unexpected beauty of this, at times, grueling, ugly, incredibly difficult, deeply introspective journey. Like a little diamond sparkling in a steaming pile of shit
That's what I'm encouraging you to undertake.
I own overwhelming culpability--just not 100% of the blame.
You need to own ALL of it. You're a grown ass adult. Your choices were, and remain, your own. Nobody made you catch feelings for someone who wasn't your wife and then continue the relationship behind her back. Nobody held a gun to your head and forced you to do that. I don't care how bad your marriage was; you had other choices, and you didn't take them. It's nobody else's fault but your own, as hard as that is to accept.
2) I could've and should've brought to my wife a final last-ditch appeal for system improvement before moving to elevate my friendship to spousal levels of emotional disclosure.
That would still be INFIDELITY. You COULD HAVE just ENDED YOUR MARRIAGE. I wouldn't have been easy or comfortable or, I'm sure, looked upon favorably by your religious community, but that would have been the honorable thing to do if you couldn't tolerate the conditions and restrictions of your monogamous marital arrangement. You didn't do that, because you wanted to have your cake and eat it too. And that hurt your wife.
Wisdom. I will learn the routes by which friendships become affairs.
That's a start, but it's still not looking inside yourself for what made you go down those routes.
Self-distrust. I will police my thoughts, words, actions, and feelings for signs of moral slippage.
You noticed moral slippage last time, and it didn't stop you.
Vigilance. I will not allow my friendships to go unmonitored in complacency.
Same thing. Your monitoring system wasn't what failed you. It flagged the inappropriate closeness like it was supposed to. You rationalized it away.
Emotionality. I won't accept "no" as an answer when I try to share.
What does that mean?
Romance. I will allocate time to build and keep romance with my wife.
Sex. I will press to attend to my wife regularly. I will keep myself ready in case beckoned.
Those are external conditions, not internal ones. You don't have full control over the quality of your marriage because a marriage takes two people to build and maintain. You only control yourself, and you allowed yourself to make bad decisions. What will you change *inside you* to ensure your choice is different next time the marriage is in a bad place? When sex and romance are at a low point?
Willingness to embrace an affair. I will seek an affair openly in the future if my marital concerns are not addressed. (As a technique to discourage marital complacency.)
As long as infidelity remains a morally acceptable option for you, whether you openly punish your wife with it or do it in secret, as long as you are WILLING to do it again, you. are. not. a. safe. partner.
You must drop these "logical" defenses and do the internal Work.
I second the idea of showing your wife this thread and allow her to make her own decision about your likelihood of becoming safe enough to remain married to you.