Greyman, sorry you had to find us :(
Good place to start is The Healing Library (yellow box top left) - there's a lot of info to read.
I'm little short on time nowadays, so quick thoughts about your situation.
First, there are no shortcuts in dealing with infidelity. It might seem there are (like rug-sweeping), but it will come to haunt you in the future. There are no quick ways to get rid of intrusive thoughts and images, especially if you are trying to R (reconcile) (it is too early for you to commit to that path yet). Some techniques might help and someone might point you to specific threads discussing it.
Listen to advice of the posters, who have been through what you are experiencing now. Some advice might seem harsh, but most of it is to help you navigate this shit storm, to get you out of infidelity.
As I understand, your WW (wayward wife) confessed to you. It's a good sign. However, even when confessing, most cheaters tend to minimize (how long A (affair) lasted, amount and kind of sex they had, etc.). It is important that you make sure you have all the information now. Any important facts that come out months later will reset your healing back to day one. It is called TT (trickle truth). Employ every technique you find to verify that you have full picture now (Swearing on you daughter's life that you have full truth now doesn't mean anything). Your WW must be ready to answer all your questions without minimization, without trying to spare you pain - nothing but the brutal truth. You might not realize that yet, but biggest trauma comes not from the sex they had, but from deceit and lies to cover it.
Get a copy of "How To Help Your Spouse Heal from your Affair" by Linda MacDonnald. Read it yourself and give it to your wife.
Do not have sex with her until you are BOTH tested for STDs.
It might be good idea to consult with attorney to find out where you stand in a case of divorce (D). I understand that it sounds scary and you are in "I want to fix everything" mode, but this might not last and information is power. You need a lot of it now.
Eat what you can (might be difficult), drink a lot of water. Stay away from alcohol. Try to get some sleep, ask for aids from your doctor if you feel the need of it.
General consensus on this forum is that post DDay is much too early to seek marriage counseling (MC). In many cases MC had negative effect, because many aren't trained to deal with infidelity, so tend to encourage rugsweeping and try to go straight to "relationship problems" by ignoring biggest problem - infidelity. Relationship didn't cheat, your wife did. She must explore with IC (individual counseling) what allowed her to make such terrible decisions and what she must do to become safe partner for you should you decide to R. And you should see IC for yourself to help you deal with the trauma.
And the last thing. It doesn't matter what you promised AP (affair partner or OM - other man). The right thing to do would be to expose him to his wife (Other Betrayed Spouse). Not as revenge, but because by keeping their secret you become accomplice in their (AP and your WW's) crime, because OBS deserves right to make informed decisions about her life.
You will not be causing her pain. Her husband is. Contact OBS in a way that cannot be intercepted by her POS husband (FB and personal e-mail aren't good for this) and provide her with an evidence. Do not tell your WW you are doing this. And if POSOM (Piece of Shit Other Man) contacts your wife, it is on her to reject it (you cannot control that, desire to NC should come from your WW, not him).
Keep posting, we are here for you.
@DDay#1:
Me: BS, 40; Her: WW, 32
M: 10y, in relationship 15y, 3DD (8,8,6)
Dday#1: Oct, 2016, Dday#2: Jun, 2017
AP#1: COW PA, AP#2: EA/PA 3 months, AP#3: COW PA
Currently (2024): Plain of the Lethal Flatness