I don't think men have the market cornered on being eviscerated by a spouse's affair. I have a pretty healthy imagination, and the picture of them being together doing anything - even her sitting in the front seat of his car - puts a ball of frozen lead into my stomach faster than I can even complete the thought.
But you might be on to something - in my case OW was also someone that we know, someone we've sat with at parties who knows me and knows that we have children together. I think that definitely makes it worse - knowing your spouse could (a) do that to you and (b) the OP who knows you could do that too. It's a double whammy.
I like Cali's suggestion for detaching as GAL so much that you're too busy to think about them. That seems so much more doable than just trying to think your way through to detachment.
It seems like many of us are in a similar stage right now...
Me : 42 Him : 43 M : 18, T : 19 D13, D11 4/16 1st BD (ILYB) 11/16 H wants s, moves out of br 1/17 H rents house & moves out 2/17 OW (he denies PA but EA last winter) 5/17 I filed for D 7/17 D Final