Or how could I best validate his feelings around that?
For me I loved it when my W would just hug me and tell me she loved me and it would be okay and then ask me how can we fix or get past this. Thats it... all I needed was to know I was still loved and it would be okay whatever happened. Sounds stupid but that's what I needed.
You can not change your past, but you can ruin a perfectly good present by worrying about the future.