OP- hugs and congrats for your son successfully launching into adulthood!
As you know, one of the pleasures of being a grownup in the workforce is having friends who are younger, the same age, and much older than you are. Early in my career I served on a non-profit board and became friends with a VERY cool 85 year old; was mentored at work by a fantastic 60 year old who became an actual friend once he retired, and had friends across different social networks, demographics, etc.
Time for you all to burn some sage and let the demons go! Your son has become a successful adult with a well paying job- for most people that’s a cause for a victory lap, not for rehashing whatever decisions were made decades ago. Hooray for you!