I don't see the affair lasting very long if he has 4 kids. OM's wife may press things and that can lead to D and that can temporarily push the APs together.
But it's just too much of a leap and chore to instantly become a step mom (as if the kids will welcome her) and his background and faith will not help him seamlessly remarry.
For you, remember -That which we resist, persists. Back off that issue and stay in your sandbox.
You have work to do on you.
How is that going?
M: 57 H: 60 M: 35 yrs S30,D28,D19 H off to Alaska 2006 Recon 7/07- 8/08 *2016* X = "ALASKA 2.0" GROUND HOG DAY I File D 10/16 OW DIV 2/26/2018 X marries OW 5/2016