I liked the flashback too. It was interesting seeing Tony as a shaggy haired teenager. And the actress playing middle-aged Livia seemed to do a pretty good job bringing that character back to life.
I think the abruptness of Tony B flying off the handle at Kim is not unlike how Tony S reacted to Ralphy Cifaretto. And that wasn't the first time we've seen a character make a sudden exit from the show in an unexpected way.