My situation is very similar, except that when I quit my engineering career 12 years ago it was because I wanted to quit. I hated it. And I've felt no shame or remorse about it... I'm just not career-oriented. Many people aren't.
But I agree that it has an isolating effect, because I couldn't really expect my school friends to understand why I didn't pursue a professional career like they did. I had one friend in particular, who I kept in touch with... I never really told him what it is that I "do". While he's been out managing construction projects and dealing with executive stress, I've been at home, mostly relaxing and taking it easy, dabbling in philosophical pursuits, working on a few minor renovation projects, making a bit of rental income... gardening, playing with my cats and dogs, walking around in the woods, salvaging old junk, tinkering with this and that, enjoying the sunshine, talking to people on the internet, learning about things that interest me, laughing with my sister, helping my mother with stuff, and a bunch of other day-to-day items that the passage of time has nicely blurred.
I have no resume and I don't care. Financially I'm ok, and my expenses are almost non-existent. Socially I'm a recluse, yes, but that's something I can work on, in my own time. And as for my school friend, well he's burnt out now from his high-pressure job. He's no longer the fun-loving person I once knew. I know that not all professionals end up like that, but I certainly would have. Looking at him is like looking at another version of myself, had I stayed in a job that I hated.
So you and I have this parallel in our lives, but we obviously feel very differently about it. Maybe we could try to figure out where the difference lies?