You say: "I have never been so lonely in my life yet live with a spouse and 2 adult children within walking distance." and yet you also immediately seem to point out to the Kind of Connection you are seeking that is not simply Being With People, in your next sentence.
So my question is; Since we all are Individuals with our unique tastes, hobbies, interests and strengths and vulnerabilities, have you not explored your close areas or community to share Your Interests? I still try to connect people over meetup.com, for example, in the hope I'll strike a conversation, say in a coffee shop. Or attend talks and community groups promoting what you might like to do, too? It's a sincere way to belong to a group where opportunities for further friendships might spawn. I do that by attending library events but to no avail yet but not giving up -- next one is to join a diabetes support group where I hope to contribute my experience toward avoiding or dealing with it. Even a group along mental health I'm seriously thinking about. So wish me luck --and I wish you luck too!