You beat me to it. Actually July, 16, 1945 when the ‘’gadget’’ was tested. Oppenheimer knew all too well what he’d done. “I have become Death, destroyer of worlds’’.
Oppenheimer was a windy gasbag too.
Nuclear research, despite being weaponized, gave the world a lot of good things too: X-rays, MRI, cancer treatments, etc.
Nuclear war, horrible though it would be, would not end life on earth. See: Chernobyl where plant and animal life thrives and is overwhelmingly without genetic defects.