I think relationships can survive nearly anything – as long as both partners are clear on what it is they are surviving from.
Maybe you are "lucky" in that you caught an early-stage emotional affair. It’s not possible to quantify pain or damage from infidelity, but I guess we can assume discovering it early – and assuming no intimacy has taken place – would make possible reconciliation "easier" than having a d-day had this progressed to full-on sex.
What I can tell you is that if there is any major factor left out of her story – then that factor will possibly prevent you two from ever having a good marriage. I put immense importance on marriage, and frankly I would never want to be in anything other than a potentially good and always getting better marriage...
We see this all the time here. Stories where a spouse has had suspicions for years and/or learns of a long-past and long-over affair. Just as devastating as stories of those that are discovering active ongoing affairs.
I can more-or-less guarantee that it would be better for you to be told NOW that they got intimate in the infirmary, rather than discover a year from now that they briefly kissed.
We often talk about the loss of trust on d-day, and one of the biggest hurdles facing us betrayed spouses is how to reestablish trust. What is often overlooked is that by withholding the information we need, the wayward spouse is showing US that they don’t trust us with the truth – basically a lack of trust. Now imagine a marriage where neither trusts each other...
To rephrase what I already said: Learning about full-on sex NOW would cause less damage than believing nothing happened, and then learning about a kiss some months from now. What that discovery does is tear off whatever scab of recovery might have been forming. It removes the traces of reestablished trust and makes you seriously question if it can ever be rebuilt.
I understand your questioning about how they met. I’m guessing refineries have a high male employee ratio, and she sees several clients per day, thereby probably a majority male. Why did this one get this close to her? Why did he get her number, versus her work-phone (I’m assuming he got her mobile). Does she offer her number to others she tends to at work or was this an exception? Why did she want to talk to HIM? Did she realize or understand that it might be inappropriate? Was this out of work hours? Did he have an exceptional medical issue that warranted this added interest?
I’m not one of those that think a woman can’t have male friends or colleagues. About half my coworkers are female, including the two I work the most with. We are friends, have an amicable relationship, often eat lunch together, travel together and all that. Yet there is no romance, flirting or anything of that nature. Your wife could work in an all-male environment and get hit on a dozen times a day, but with the correct attitude just cast it off like rain off a duck...
I think the important message you need to get across is this:
More than NEARLY anything you want to reconcile. You want to have the BEST marriage possible.
But you have realized a some things:
One is that if she is having an affair, then you have already lost her. She is totally free to choose OM, flirt with the workers or whatever. But not as your wife. Accepting that the marriage is over is the lesser of two evils for you. If this is what she wants then it’s better that the two of you accept it and move on separately. You are willing to commit to as amicable a divorce as possible, if she chooses her infidelity over the marriage.
The second is that your foundation for trust shattered on d-day. You fully understand that marriage can’t be built without trust, and you question how you are supposed to regain that trust. You can’t even trust her swearing on your children’s lives, because she also swore to be yours at one point. Make it clear this isn’t what you want – you do not want to not trust her. It’s just what it is. You need a base to rebuild the trust from.
The other thing you have realized is that reconciliation is going to be hard. To make it slightly easier you are offering her a temporary amnesty to be totally 100% truthful about what happened. Make it very clear that NOW is the time to be absolutely 100% truthful and no matter what she might share, you are willing to commit to reconciliation. If she were to tell you NOW that they kissed, had sex or shared intimate information then that would be something you could deal with. If however you were to learn something a month from now, that would set you back to d-day, and you aren’t certain you would be able to deal with that.
Not only that, but by not being 100% honest she would be telling you very clearly that SHE didn’t trust you. That would be devastating.
Then tell her that a polygraph would be to both your advantage. If she is truthful then she will pass, and if she passes it shows you in a logical and sensible way that she is being honest. That in turn places the onus of rebuilding trust on you because the poly says she’s honest.
Finally – Your drinking is an issue. Not to justify her affair. But it does impact relationships. Take your sobriety seriously.