Stupid is an essentialist insult. I'm describing behavior. Not knowing something is fine. Being offended by the explanation is baffling.
You demonstrably expected an explanation for what I said. Which I gave. And that somehow made you act even more hostile and defensive.
Third time: what else am I supposed to say?
If there is some way to deal with this, that you would not consider degrading - what is it?
if there is no way someone can question your comments, that you wouldn't consider a personal insult - how would anyone communicate with you?