When you are at the point of completely losing it with your kid -- what do you do to calm down?

Walk away. The best thing to do is to walk away. Have someone take over and walk away from the scene. Go for a walk downstairs, go for kopi at the nearest coffeeshop. Put on your earphones and just listen to some soothing music. Go play a game on your phone. Go for a jog. Do whatever you like. Just.Walk.Away.