forgot to winterize and it went to 21 last night

Regarding the pump failing to not prime. I had the same problem when I tried for the first time to winterize my trailer. I installed the Camco winterizing kit which is a T setup with a hose that goes to the gallon container. I had to pour antifreeze into the tube and have it run down to the pump. Eventually the pump membrane caught some fluid and it began to pump on its own.