pain can be mental or physical. sometimes when it’s mental people change it to physical because mental pain hurts a lot worse than any physical pain.
pain is caused by life i guess, human nature.
maybe you fall, or get cut or bleed.
or maybe you feel empty, sad or hopeless.
these are all examples of pain.
"To the pain" means the first thing you lose will be your feet below the ankles, then your hands below the wrist, next your nose and then your tounge. The next thing you lose will be your left eye followed by your right. Your ears youy keep and I'll tell you why, so that every shriek of every child at seeing your hideousness will be yours to cherish. Every babe who weeps at your approach, every woman who cries out "Dear God, what is that thing?" will echo in your perfect ears. That is what "to the pain" means. It means I leave you in anguish, wallowing in freakish misery forever.