G, no there was no OW. He was 25, MIL was 19. Babies. WH was an 'accident'. They were young, a summer romance. MIL a pain in the butt. FIL saw it & thought he couldn't stand a life-time of that! They were not married when she fell pregnant. Small village, Catholic. They were forced to marry by the parents. It was the 60s! Horrible story, really. NM, I don't think it's so much BS, but yes, FIL was feeling so crappy about the whole thing that he put blinkers on and didn't have the guts to check in with WH and the whole sitch when WH was growing up and see if he could play a role in some way. In this, I agree, he is totally at fault. I don't think he is a changed man, but then what do I know? I suspect though, he is 67, lonely and has regrets.
Do let us know if it's a good book. I SO need to read something like that!