I think the hardest thing to recover from is uncertainty. I also think that we can recover from nearly anything and everything we know.
I also think we need to accept we never get revenge or payback. You can’t "unaffair" your marriage. You can’t have her do push-ups or go to bed without dinner to make up for what she did wrong. Your options are to end the marriage or work on how the two of you move on with the intention of making the marriage good. Not because of the affair, but despite the affair.
I think that if you were to look at your wife and be thinking "did she ever do anything more than the oral sex she has confessed to?" then that thought could prevent you from ever feeling safe or as if you did right in remaining in your marriage.
To be blunt and gross… but in the context of the issue you are dealing with…
If she shared NOW that they had done sexual acts that you don’t even have the imagination to thing about, or were never on your marital-sex-option menu, then that would hurt. But I can promise you that it would hurt even more if she convinced you now that this was only a couple of BJ’s over a 2 year period, only to discover maybe six months from now that they had a couple of quick but relatively traditional sexual encounters in the gym.
Basically – your imagination can conjure up worse scenarios than reality, and her holding back truths now that are discovered in the future will damage whatever trust might have been reestablished. IMHO to recover you both have to reach a stage where she can honestly shared what happened, and you believe you have a clear picture.
However…
Be careful on what to expect. Some of the issues, like did you love him and all that – the emotional aspects – are only semi-valid. Fact is that she didn’t leave, nor did he leave his family. The emotional aspects are likely to be justifications rather than any "real" emotions. Infatuation rather than true "love".
Also… keep in mind that human memory is fickle. She’s going to remember if they had sex. But it’s unlikely a) that she remembers or b) that she admits if she initiated. Who led whom on. In fact – it’s likely she will deflect as much blame on him. Just keep in mind that at each and every step – up to the first time they kissed and onwards – she had the option of stepping back.
What she tells you should be the truth as she recalls it. What that means is that if she were to tell you that the sex started in October and took place maybe 10 times then that might be true to her because she doesn’t remember better. Maybe you find some way to prove that it actually started in September and they hooked up 12 times. Doesn’t have to be a lie from her – but rather her recollection of events.
How fickle memory can be is why witness-statements are a defense attorneys dream, and a prosecutors nightmare and have a shelf-life shorter than dairy.
I’m going to suggest the following:
Let her know that at some point very soon you need the truth. When it started, who initiated, what happened, what they did, where they met, sex in your home, your bed, your car… whatever you need. Remember you can’t unhear – but I truly think your imagination can do more damage than reality.
Tell her that the fact you are still around is a strong indicator that above all you wish to reconcile, but you can’t reconcile without knowing what happened. That honesty is the ONLY WAY to go forward.
If you are emotionally able to then commit to a period (say 6 months) of healing. At the end of that time you are going to evaluate if you believe she is committed to the marriage (as in having shared the truth) and if you then believe you two can make this marriage something you both want.
Tell her that NOW is the opportunity to share the truth. Tell her that seeing how long the affair lasted you have a hard time believing this was only oral sex. Let her know that you need to be convinced you have the truth and that discovering you don’t will cause MORE problems than whatever she shares NOW.
Let her know that at some point – and that point won’t be too far from now – you will require a polygraph to convince you that you have the truth. It’s not a tool to embarrass or shame her, but a tool for HER to show you that she is being honest in her story.
Just keep in mind: Polygraphs measure honesty and not the truth. Like if she believes they had sex less than 10 times but you KNOW it was 15, she will pass with a "no" if asked "did you have sex more than 11 times".