Jones, long time lurker here.
I can really feel your pain. I was in exactly the same boat as you 4 years ago. Again H went with OW at work.
We are still together. I thought I would never, ever say this. But things are good. It's been a long long road.
If you feel like I felt, maybe subconsciously you are acting like you are, to test your H's reaction. Hoping for that massive declaration of love and forgiveness, for his stupid actions. Mine never came as that declaration. I pushed, shouted, sobbed, trying to drive him away. He, on the other hand, did as much shouting and sobbing, but he didn't go. For a long long while, his affair just consumed my whole life. Trying to piece every movement, reaction and conversation...it was so exhausting.
You may not stay together - if you both don't want to. But if he is showing signs of remorse and demonstrating that he is willing to change then give it a chance. It's not easy, I think it's easier to split sometimes.
FWIW, the OW still works for the same company. I hate that fact. Especially as in the first year, she blatantly tried to sway my H, by texting and continuing to pursue. He did try the 'well, I have to work with her, so I have to speak to her' - now, there is only formal emails and no other communication. I have access to all means of communications. He has consciously tried to keep me posted on his goings-on at work, and whilst I'll never be the same person pre-affair, I'm as confident a person as I was before.
My H is not the most communicative person in the world. Culturally different to me, but our relationship has resumed to the one we had before the whole sordid affair. I judge him from the man I've known for the whole of my adult life, and try not to pin him down on those couple of months he was a complete bastard.
Hope my post gives you so comfort, and hope.