Hello, Brokenness. Welcome to the greatest club that no one ever wanted to join. I'm sorry you've had to find us here.
I certainly encourage you to come back and post again. While replies can often be overwhelming, the vast majority of folks here mean well and hope to help you find your best path forward.
For most people, the betrayal of infidelity is a profound shock and a severe emotional and psychological trauma. What you've been going through is quite normal. Take some time and do a little research on post-traumatic stress disorder (PTSD) and I think you'll find a few of the symptoms quite familiar.
One of the most important things you can do for yourself right now is to focus on you, your recovery and healing. See your PCP and let him know what you're going through. Chances are, he's heard it before. A good IC (individual counsellor) can also help your recovery and healing. Eat healthy foods, "hit the gym," get back to some old hobbies, whatever. Forget about reconciliation and forgiveness for the immediate (long-term) future.
If you look at my tag-line you'll see that I'm heading towards a divorce. My stbx also had a ONS at a work function (a trade-show out-of-town). Being suspicious, I picked up her phone one Sunday afternoon in April of 2015 and found enough text message with the OM to confirm my suspicions.
My son was only 4yo at the time. Hardly two months after d-day, I was calling lawyers and seriously looking into a divorce. I couldn't pull the trigger, though. I couldn't bear the thought of my son's world being ripped apart. Today, I'm much more okay with it. In fact, I'm quite happier.
The first week I was faced with her telling me she was not in love with me anymore and we should seperate as I would never forgive her anyway.
She had been unhappy for over 12 months and out of love even longer.
Yeah... that's gotta fucking hurt. One of two things might be going on here. Wayward spouses have a habit of rewriting the history of their marriages and shifting blame on to their marriages and/or betrayed spouses in order to justify choices they know to be inherently wrong. On the other hand, she might be telling you the truth, that she was, like my own stbx, giving separation or divorce serious consideration. If that's the truth, as believe with my own story, this was your wife breaking away.
The more I press her for information, the more this pushes her away and I know that the response will be that I should cut & run but each time I've taken the hard stance, it emotionally breaks me. I second guess myself and believe I am causing more damage with my constant interrogations.
It seems to me that more often than not a WS's behavior after discovery can do more harm than the betrayal itself. Whether it's an affair going further underground, continued lies and obfuscations, defensiveness, deflections, blame-shifting, gas-lighting or just general assholery, all those little traumas end up causing more and more damage.
Most of us second guess ourselves and for very good reasons; infidelity is crazy-making shit. There's a great essay in the "Articles" section of The Healing Library (see link in yellow-shaded area at the top-left of the page) entitled: "Joseph's Letter." Even if you don't give your WW a copy, it's a great read.
I just don't know if I'll ever get passed the image of another man screwing my wife. I also worry that we will slowly drift back into our old life and then I'll start to just feel resentment towards her. I know our relationship will always be stained with infidelity and it has lost it's innocents but is there really a light at the end of the tunnel?
You'll get rid of those images. Eventually. When you're give-a-shit-o-meter gets pegged, you stop caring.
Slowly drifting back into your "old life" is certainly a possibility. There is, however, "light at the end of the tunnel." Some couples are capable of reconciliation and building a new version of their marriage. Some WS are either unwilling or unable to do the work that R requires. Some BS, like yours truly, eventually figure out that they'd be happier divorced. Either way, the light is yours to create, brother.
Focus on you, Brokenness. Step-back and detach from your WW, watch and observe what she does with the opportunity you've given her. Focus on your recovery and healing. It took me a good ten months just to recover and years, my friend, to heal. Find your own peace of mind, body and spirit, for, ultimately, we are all responsible for our own happiness and well-being.
Keep reading and keep posting. Stay strong.