Sometimes you just have to be angry.
I usually keep my temper under control, locking it away in a heavily-guarded vault somewhere in my head, because custom dictates that we converse politely with other people as far as possible. But there are times when the door of the vault gives way, and most of the frustration and the venom rushes out with all its ferocity. And as the old memories come back to haunt you, faithfully recalled by your over-efficient brain, you just have to let yourself loose.
I guess you deserved it.