Do not take sides - support them both and especially the GC. I'm sure your son knows how angry and disappointed you are with him. I'm sure he is feeling a right heel at the moment. and clearly worried that he's really blown it. This may well be the making of your son. Maybe he needs to risk losing everything before he finally grows up.
An affair does not necessarily mean the end of a marriage. Surprisingly it may actually make their relationship better. However there is a lot of anger, pain etc to be worked through first and that takes a lot of time. It's probably clear that I'm talking from bitter experience. I wish it had never happened but then if it hadn't, I doubt we would be where we are today, happier than we've ever been. It is not your fault, as an adult he is responsible for his own decisions.
I feel for both your DIL and your DS. It's simply horrible. I wish you all well.
Lighthearted - How long do you display Birthday Cards?
Are You Finding the Hot Weather is Making you Short Tempered?

