Sorry to hear about your wife.
I disagree with your son. His statement implies that pinball is essentially preventing you from having a life which, from your description, isn’t true. Like almost any hobby you can enjoy pinball by yourself or with others. Other than team sports, most things are really individual anyway. I’m sure the advice you receive is well intentioned but “don’t be too secluded” seems insulting. I would say as long as you don’t deliberately seclude yourself there’s absolutely nothing wrong with liking to stay home. People see my basement and wonder why I ever leave the house ...
Do what feels right for you. Thank your son for his concern, but pinball sure doesn’t seem to be a problem here.
I think Phat_Jay got it exactly right.