Your situation - that is your thoughts and anguish and confusion are normal.
Seems to me you rug-swept your wife's dalliances and/or just didn't get the tea-leaf readings right.
Your pains are normal and not to be ashamed or denigrated. Why? Easy - you found out you have been living with someone you do not know! Lies by omission - "What he doesn't know won't hurt him!" Well - you fleshed out that one omission of multiple ONS by threat of polygraph. Good move for getting the truth. But, like a kid with a gun (think 5 year old) you just shot yourself (in the foot?) There is only one way through your pain and that is talking through your thoughts - IC - and your wife.
Concern is words in other post (I didn't find them) that your wife is thinking of divorce if you "can't get over this" or words to that effect. This is a MAJOR RED FLAG! If your wife was/is really invested in marriage and family - then she should be willing to walk over broken glass to work on finding a path for BOTH of you to heal. Yes - BOTH
You have to heal yourself and you can do it with her by your side in the future - or with her not by your side.
Either way - you have to find your path to peace on your own. If wife is willing she can assist but the wheel of the ship is in your hands. I would suggest you get the book:
The Body Keeps the Score: Brain, Mind, and Body in the Healing of Trauma
by Bessel van der Kolk M.D. | Sep 8, 2015
You have to find a way to live in peace with the memory of what she did. Together or separated and you will have this memory the rest of your life (barring Alzheimer's) - this will take work on your part and plain old time. Years -
One thing to keep in mind is both of you have changed over the years. Your opinions and assessments of things that occur in life have morphed - sometimes for a less forgiving opinion and others for - well - that is life - we go on and "just let it fade some" but yet never forgetting. You have a friend that turned alcoholic and then got clean. He is still your friend (?) and you know he did a bad thing but you were not the object of any mistreatment and didn't observe any that violated your morals - so you keep him as a friend. Your wife is no longer she "was" a decades ago. You want your pound of flesh for her sins on your marriage but that event has so long passed - the "getting the pound of flesh" will not make your marriage better. Maybe, for a moment, your inner Alpha will feel good at seeing her suffer - but long term - making her suffer will also make you suffer when you realize you did something for revenge or "to do unto others as done to you." (apologies for mangling the phrase) If you truly still love the person you have lived with - say the last 10 years - then you should realize that love is actions and your "getting a pound of flesh" is not a loving action.
Your wife - should be your best friend. Your post leads me to think you "broke up" six times and her "go-to" to absolve her "hurts" is to get porked by some dude? Really? From your post I gather you were both still on the road to "adult maturity." I think we all did some SXXX in our late teens or early 20s that would shame us today. I think you need to consider that with your IC. You need to flesh out if she still harbors the opinion that if you have a serious issue - she hits Tinder of Craigslist for emotional medication. If you find that she is still of that persuasion - you need to see a lawyer and start plotting your future with your fortune being the most important issue to discuss.
Getting back to "divorce" if you can't get over this. This also tells me she has some self issues. To her (for suggesting?) says "I think I would hurt less if I divorce rather that go on for the long slog down the path of reconciliation." Yes - reconciliation is a long path - the rest of your time together if you two manage to stay. My bet is you both have some stuff to do - change in habits? Choice of words when talking?
(about anything!) - consideration of the others opinions? Dealing with life stresses? Family relations?
I probably missed a minefield or two but you need to make a list and start working on all the things you thought were OK and make sure they still are or not and need work.
Your posts convey to me (my interpretation) is that you want to stay with her more than not. What you say about her is pretty much the same. So, if that is true - you must start to think carefully of what you do and say as you are walking on thin ice and need to work on finding a way to work on finding each other.
Make a list of all you still like about your wife.
and a list of what you don't
Make a list of deal breakers and discuss with someone who knows you or in IC
I've gone on to long (good thing I haven't hit the Marsala yet!)
Others will post soon and give you more suggestions so buck up for the long haul. Looong haul.
After-thought - I am assuming fidelity has been the norm since the confessed "kiss."
We here know the confusion you are experiencing - so give yourself time and find someone to talk to about all of this. Talking helps in that the brain has to work harder to "order speaking" and hearing words helps cement the meaning. The meaning when spoken can often reveal wrong thinking.
I am thinking you wish to run the Gauntlet of reconciliation - so you need to realize the process is long.