What happened in the ending of coffin in the anime?

All I remember was that gojo was quite terrified and sick after the coffin game. The actual ending went so fast and I really couldn't read much that was happening and basically went completely off of the images that were displayed... I get Gojo cuz it was pretty traumatizing even seeing the images... but i dont want to have to go back and rewind every single sentence and take apart every detail... does anyone got some explanation of what happened?