I think it’s you that determines what level of assurance and truth you need. You CAN decide you have enough but realize that you then need to embrace that decision. Trying to reconcile with constant doubt doesn’t work. This is why I emphasize knowing the truth
Truth can have various forms.
Some truths are constant: 1+1=2
Some are relative: 500 years ago, we thought the truth was that the Sun and planets revolved around Earth.
Some are subjective: If you truly think you saw an UFO then that’s true to you.
I can accept that your W truth might not be “true”. I can accept she’s forgotten a lot. I can accept that some of what was true +30 years ago isn’t and maybe never was true. I can also easily understand that she might forget things. Like if you ask her if OM was ever in your car, or if she wore the bracelet you gave her that Christmas when out with him… Maybe she truly doesn’t remember details that don’t hold the same value to her.
But frankly that’s not the truth I think you need. In fact, it’s not so much the truth you need as assurance. That assurance can be gotten by using the truth as a tool.
The assurance you need is that you can gain a sense or feeling that you know the main bits. You need an assurance that your wife trusts you with the truth and is committed to recovery.
For example: If you were to ask her if she ever met OM after the affair ended:
THAT would be something she would remember. THAT would be a classic yes or no poly question.
If she tells you no, then fails a poly you know she’s not being honest.
If she tells you that she ran into him by coincidence at the Mall back in 1997 but didn’t talk… THAT would be an innocent, non-planned encounter and knowing it beforehand would enable the operator to reword the contact question.
If she admitted the affair started again 1994 for a weekend in Reno then that too is something you could digest, appreciate she was honest and evaluate the effect on recovery.
However, … If you were to discover by yourself that either of the two scenarios, I listed had taken place after months of MC and IC… THAT would be more damaging.
Personally – if I were in your shoes – these three questions would be on my poly list, and by passing them I would feel a lot safer moving on.
(i) being assured that the affair was over when she says it was over,
(ii) that there has not been any contact since when she says there was last contact
(iii) that other than OM and you she has not been intimate with another man since you married
But then mrplspls, paying a specialist for advice and guidance only makes sense if you follow what they say. Maybe check better on the truth-issue because I honestly don’t see how my three suggestions can be forgotten. Yet IMHO they might hold the key to recovery.