If your dad gets that way by drinking too much, talk to the bartender! Perhaps you could ask him/her to put very little alcohol in his drinks. Or, assign someone to keep an eye on him and distract him to keep him from drinking too much. But you should really think long and hard before not inviting your own father... talk to him about his behavior at your sisters wedding and tell him how much it would hurt you if he acted that way at yours. Not inviting him could cost you the entire relationship, while inviting him might just mean a bit more work and effort... and remind yourself that you shouldn't be embarrassed, you're not the one acting that way!