Red, I wanted to say I think his feelings for the OW are real. They are childhood family friends and therefore they are not starting from scratch. I think also the fact that he will be living with her very far away means he does not have to face me and the chaos here.
I do believe relationships born out of lies and destruction are doomed, however the distance makes me thinks they'll 'get away with it' because I won't be there to remind them of what they've done. Plus they are probably going to do their damndest to make it work given how much they have hurt so many people.