Every time you find out something new it resets the clock on recovery. The fact that it took a year for you to get what you think is the full truth tells me your most recent d day was probably a year ago, and that's assuming you now have the full truth. It's called trickle truth. That's the relationship killer.
The affair itself is bad enough, but the way a wayward spouse handles discovery is what usually makes or breaks a marriage. Every time you think you know everything then get blindsided with another detail it reopens the wound and makes it fresh again. When you're constantly reacting or recovering from new info, healing can't really begin.
Dismissing and minimizing is a killer too. He needs to own what he did and recognize the damage done. Betrayal trauma is real trauma. It takes on average 2 to 5 years to recover from infidelity, and that's when everything "goes well." PTSD symptoms are common for betrayed spouses.
Have you or he done any counseling? Not marriage counseling, but individual counseling. You for the trauma, and him to dig into what it is that made him think an affair was a good idea. Marriage counseling might be helpful down the road, but the marriage isn't who cheated on you, that was him. It doesn't matter what's going on in a marriage, infidelity is never, ever the answer. No marriage is ever saved or fixed by bringing another person into it. You can be partly responsible for the state of your relationship, but he's 100% responsible for his choice to cheat. Just know that. Nothing you did or didn't do made him have an affair. That's all on him and he needs to own that.
I'm sorry you've found yourself here, but there's a good group of people here who know what you're going through. You'll get some good help and support, so stick around and keep posting. Ask questions or even just vent if you need to. This is the place for it. Just typing things out and getting feedback helped me a lot. Just hang in there.
[This message edited by Pogre at 3:40 PM, Friday, May 29th]