We do something that looks a little strange in art, when we're trying to solve for why a composition doesn't feel "right" or doesn't "work". We'll take the image and turn it upside down... and then look at the balance of objects, the balance of color, and how the eye moves across the image. Sometimes we even find a way to improve the image!

Your experience reminded me of that because you expressed all the elements you need to solve the remaining questions you have about it. The answers are there; it's just in how you're looking at it that is evoking the questions.
The big question you posed, about the feeling of being put down because you connected with your son's experience (and consequently, recognized your own past feelings)... is one of those "interpretations" that we impose on other people based on how we were treated by the insufficient, cruel, or negligent parents of the past. It would FIT if it was your Dad implying that "it was all in the past" - be a put down, that is. He would be denying you the right to your feelings and his responsibility for his part in your feelings - which are truly outside of time - and until you've resolved them, will continue to occur when tweaked by a present day situation.
But from another person - even a friend - it's something else. It's meant well; to help soothe and restore your equilibrium, I think. To help you resist the magnetic pull into the old black hole loops of feeling bad... paralysis... feeling bad... etc. It's meant to remind you that except for emotional processing and healing ["except" is admittedly a LOT], there's often not a lot we can do about old hurts: we can identify, acknowledge, soothe again (for the nth time... there's always an "again") and then turn our attention to handling the things we can do something about, in the present. Sometimes, we can even find ways to address old hurts by dealing with more current ones... from our new place within ourselves.
You didn't say how your son felt. Was it an important issue for him? Were his feelings hurt? Did he just shrug it off? Like it was no big deal? Or does it bother him? Does he know it upset you and why? And does he want a "mother-tiger" defending him? Or will he decide to work it out for himself?
I know I have to be careful with my girls - when something happens to them and they're expressing feelings or trying to resolve an emotional predicament - I have to make a conscious effort to not let bits of their experience click into my old crap... and then express that back to them from my old wounded perspective. It's just not the same situation for them; even with my mom - it's a whole different set of circumstances for them, than what I deal/dealt with. Sometimes, they even teach me things or put something from the past, to rest!!
I do know these things have to be expressed - somehow, somewhere - or they're like an unnoticed drop of battery acid that in time burns right through skin and bone.
Bounce it off your new armor, GS... you don't have to go "back" anymore!!