But I don't think that Tom really lost his temper with Sonny in that scene. I think it was more of a "wake up, see what you're causing?" type of outburst. I don't think that he was actually mad, but more that he spoke in a raised tone of voice to make Sonny realize that he was serious about what he was trying to tell him.
Don Cardi
Agreed, which is why I said "close to losing his temper." As I think about this, all of the Corleone sons and daughter in one way or another let their emotions get the best of them. Sonny is the most obvious, of course, but Fredo shows his temper in the "I'm smaht" thing and Michael, imho let emotions get in the way with all his grudges and nastiness to Tom and others. Connie, also was a little unscrewed in GF I and II, although she calmed down a lot in III.