I would agree with the statement "a little self-reflection is a good idea" in just about all things/areas of life.
But the OP has been quite forthright. He has been "going over it in his head." Is forthright and cognizant about his DMing style, attitude toward this player, personally, and the past relationships involved.
The fault in this particular scenario (from all the information at hand) is the [gaming?] attitude and behavior of the player.
This is a grown man in a public space, throwing a hissy fit turned temper tantrum, shouting and creating a scene, and storming out on and LEAVING -not just some friends that he drove there- but some friends and his girlfriend of 8 years!
I don't care if it was a D&D session, a dinner party, a backyard BBQ or a gala fundraiser, the player's reactions and behavior were inappropriate and uncalled for, at best, and at worst belie some underlying emotional/behavioral/personality issues.
Dump him from your table, dump any table he's sitting at, and dump any people that would support/defend his actions and behavior.