What I find more amazing than your WW's message is that this obit book was set up by his EX-wife. I suppose she did this for her children's sake, but still. This guy must have been a really smooth operator.
If it makes you feel any better something similar happened with my sister and her husband. About two years after a very rough period in their marriage in which they almost divorced, her husband got a call one afternoon, after which he sat and cried. He finally admitted that the rough period was the result of an affair he had. It had long since been over. Her mother had just called him to tell him she died.
The mother wanted him to not only come to the funeral, but drive her and his AP's sister to the funeral and escort them all day. And it was on my sister and his twenty something anniversary no less. My sister was in such shock, she told him she didn't really care what he did. So to my astonishment he went. I don't think he actually drove her family members anywhere, he just drove the 140 miles to her funeral and then drove back.
To this day I think that was horribly disrespectful to my sister.
But my sister seemed to understand that he would have resented her if he wasn't able to say his goodbyes and she seemed to feel it was a gift that immediately upon finding out about the affair the threat of her existence was gone. She was obviously crushed about the affair and they went through some rough times but I can honestly say their marriage is truly stronger than ever today. He is remorseful, completely transparent and exceedingly thoughtful in everything he does for my sister. So I've seen a case where you can get past this, particularly because the AP no longer exists.