Ok this one is easy. Actually I have a number of someone(s) that fit the cannot be forgiven listing but here's one - My Standard 1 Class teacher.
I'm not sure whether she's still alive or not but her name is Mrs A. Ganam (can't remember the spelling though but she's an Indian lady). She was my class teacher and why I cannot forgive her? She actually accused me of stealing the story books from the class reading section at the back of my class. She not only accused me, but she also punished me by hitting my hand using the ruler despite me denying furiously. I mean sure I love reading, but why would I steal the class collection when I have stacks of story books at home?
So Mrs A Ganam, I hope you have a horrible life since you have ruin mine when I was in Standard 1!