Why were you mad? Because he cashed out? It's his money to do whatever he pleases with. As soon as you put the money in the pot they are not your's anymore. Why bother what other players do. I'd rather think of my own game and try to win as much as possible myself. Sure it can be very frustrating to get "hit'n runned" but playing with emotions involved is the best way to lose a lot of money. Take a deep breath and count to one million or whatever or just leave the table. Kick the dudes ass another time when you have your emotions under control.

Personally I don't see the point of cashing out before you are to leave the table. I prefer beeing the big stack who can afford to set anyone else all-in whenever I like.