From Tiny Monsters, which deals with my firstborn being four, and one of my own early memories:
I have something of a monster antidote: breathing. Breathe deeply and calmly. Get oxygen into that part of you that fears the tiny monsters. Once you master calming your hurts and fears (or at least calming the adrenaline that would make you lash out), you'll have time to think about how to deal with them rationally and sweetly and compassionately.