halacha - At what temperature is a food Boleya in the utensil

Say I have a pot that I used for beef soup. Then an hour later I forgot I used the pot for meat and I decide to make soup with cheese. I throw the cheese in it and put it on the fire. About 5 seconds later I remember I used it for meat. What is the Halacha, does the pot need to be kashered, and what is the Halacha regarding the cheese.