I think it was a parental mistake. You blew it and I do think you owe him an apology. You also owe it to yourself to learn some language that puts him in his place as your minor child without reducing him to dirt. He is bone of your bones, flesh of your flesh. You don't want him to feel crappy about himself, just to develop a sense of worth that comes from accomplishment, not entitlement. Help him to accomplish something he can be proud of and let him know YOU are proud of him. I think he is going to need some extra reinforcement there. That speck of dirt comment may be hard to wipe out.
If this was monumentally out of character-then it will have hit him harder, but he will also not be permanently wounded if you remediate it a bit. If you do that all the time, you are going to have a crappy life as a senior citizen.