Rule #1: never bet on a team you have any emotional tie to.
The converse to this is also true:
Rule #2: Feel free to bet against teams you have an emotional tie to. Its called a hedge. Team wins = happy. Team loses = not quite as unhappy since made money. And, the bigger the game, the more you should feel free to bet as the bigger the win, the more money you don't mind losing. And the bigger the loss, the more money it takes to make it not hurt as bad.