That is so sad. And it's also what I fear will happen to me.
I have never been married but had a relationship with someone I'd rather not think about too much anymore. Therapy helps. It would have been so wonderful, I think, to have a loving relationship. That's what I looked forward to when I was young anyway!
You write that when you go to groups you don't feel they make you feel welcome. Why is that, is it because you expect others to make you feel good in the group, being a natural wall flower maybe? Or is it because you don't feel you belong?
When I went to groups I would usually end up alone close to the wall, or I would sit somewhere and start drawing, or look around. I was hardly ever spoken to. The strange thing is that this also happened during Summer holidays: I would usually go out alone and take a book or sketching pad, and have a drink on my own. Some guys would usually be interested but I was not into what they were into 😀 I must say that I actually had some friends, come to think of it, in that past: guys who were simply nice and with whom I corresponded after that Summer holiday, for years! But then life happened and we lost track of one another. I do remember them fondly though.
It's sad that you lost contact with your youngest son. Do you have other children? I always wanted to have children, I never had them, sadly.