Survival in the Doomsday, Minus 70 Degrees to 60 Degrees?

On the day I built the fortress at the end of my rebirth, my ex-husband and mistress knocked on the door crying. I turned on the monitor and watched them slowly freeze at -70°C. Later, the scorching heat melted the glaciers and zombies became rampant. I picked up a special soldier, a doctor, an engineer, and a child with special powers. We grow vegetables underground, build cities above ground, and rewrite human rules in the ruins. Until the satellite images showed: an ice king rising from the north who eats frozen corpses - it was my ex-husband who was not dead. He led his army south, frozen for thousands of miles, and said he wanted me to "experience true despair." I turned around and said to my friends who were debugging the geothermal weapons: "Tell him that despair is for the weak." "And we are the first thorny flowers that grow in the wasteland."