Error during clinical

This past week during clinical my instructor handed me discharge instructions and said my patient was being discharged to home. So I went in the room and gave the discharge instructions. Well the next day on the unit we were notified that her IV saline lock was not removed from here arm. Well since it was my patient i know have to write a 7 page report on iv care and write a critical incident in my journal. I understand the seriousness of this. But anyother time we had to removed a saline lock we were told to. I know it was my responsibilty to assess the patient. But she bathed herself and dressed herself early in the am to be discharged. This is making me really upset that i did this. I wanna be successful in nursing school but right now im pretty bummed and i just feel like a failure. i need help...