Treese sounds like you and I had similar lives and values. I can tell you now don't look for answers because there are non and all the analysing in the world will not help you. Everything at best is pure guesswork and asumptions.
My x was a great family man and now he has no contact well I wrote about this years contact! He lost all his friends really after nearly 40 years of people seeing us as a couple it was hard for them to take his mistress/wife into their lives. So he now lives abroad away from all those who knew and loved him and only keeps in touch with his elderly mum and sister/family. They turned their backs on us-not straightaway but gradually overtime their loyalties were to him the old blood thing. So at gone 50ys my world disintergrated, I do understand how you feel but think you are doing a great job. You still have a young son, mine where closer in age to your older ones when it happened so they had aready left the nest or in the process of doing so. It felt like it was just me alone! I felt for the longest time this woman had stolen my life taken over my shoes until my T said would I like to be her and have my x back. The answer immediately was NO. Maybe you could ask yourself the same question.