It's almost a year since my D-day. I still have unresolved questions. I attribute this to only recently becoming compos mentis/ having full control of my mind. It seems that, with time, new questions arise and, old questions become re-framed as a result of new perspective.
This is all completely normal (although I'm sure that doesn't help much). I went through the same shit and I'd imagine that most, if not all, BSs experience this, too. Our brains, it would seem, get a little rewired after a sever trauma. Trying to understand why the traumatic events occurred is simply our brain's way of trying to help us avoid a similar trauma in the future. I'm sure I asked my FWW hundreds of questions, often the same ones over and over again. It took me at least a couple of years before I stopped asking questions and even then I had to constantly remind myself, especially when triggered, that I already had a lot of the answers I needed (it takes time to process all of the information).
("I don't remember", "haven't we covered this already" and, "how long is this going to go on" are common responses).
Unfortunately, your WW's attitude isn't all that helpful (as you already know, right?) A truly remorseful spouse might have some memory gaps. However, her refusal to engage with you, to be empathetic, patient, and to put your needs above her own, does not bode well in terms of reconciliation. I cannot recall my FWW ever making any of the above comments. She was resilient and tried very had to answers all of my questions.
(Has your WW read "How to Help Your Spouse Heal from Your Affair?")
I'm wondering if it's wise (or not) to, essentially, use the threat of talking with her best friend, AP or, the AP's wife, as leverage (i.e. a threat that, if I'm not satisfied with what you tell me, I'll talk to all of the aforementioned).
Don't threaten. It doesn't usually work. Just do it. If you believe that having a conversation with the OBS (other betrayed spouse) will help you, then do it. She might not be all that receptive, but then again, she might be able to shed some light on a few things.
Your WW's best friend and the AP, however, are probably not the most reliable sources of information. Your WW's best friend will likely attempt to dodge the situation and the AP will most likely lie.
I fear that she hasn't told me as much as she should have (I can elaborate if need be) and, hasn't -- despite IC -- arrived at a point where she understands why she had an affair (or, if she has, she can't -- or won't -- satisfactorily explain this to me).
It's a reasonable fear, brother, and all too common as well. In general, I don't think any of us ever truly understand why our WSs were capable of doing the things they did. It's sort of like an asymptotic curve; the hard we try the closer we get to the limit, but can never actually reach that limit.
What's truly important, I believe, is that your WW does everything she can to help you to understand as much as possible. It's not the end result that's important (although it certainly helps), but her willingness to be authentic, empathetic and patient enough to make even Job proud.
There is a risk she will encounter the AP at work in future and, given she has been infatuated with him twice in the past (her term, not mine), naturally, I'm concerned about what may transpire should that happen.
What, if anything, is your WW doing to mitigate the chances of that happening? A truly remorseful WS who is fully committed to reconciliation would move heaven and earth to ensure that no contact remains fully in place until the end of time itself.
Hand in there, man. Keep asking your questions. Let your WW know, in no uncertain terms, that she cannot avoid the consequences of her actions. It takes most couples years to reconcile. Years, man. Years. You'll cover the same topics repeatedly until you're no longer interested or feel a need to cover then again.