I'm trying to find a book about a boy who wears glasses, is a weakling and who was constantly bullied at school. During one of the bullying episodes, he was shoved into his locker and locked up (or maybe he chose to lock himself up to escape his tormentors. Sorry I kinda forgot). Then he passed out, and "awoke" to find himself floating, when in fact, his body was still in the locker. He then realized that he was experiencing OOBE (out-of-body experience).
He then started using this ability to get revenge against his tormentors and to snoop on other people's lives like his own father. Because of this, he learned that his father had a new lover (his mother was already dead or his parents got divorced). This worsened his relationship with his father because he thought that his father did not love him in the first place. So he decided to kill his father by planning to lock him up in the garage and poison him with carbon monoxide.
He set his plan into motion. But at the last minute, he saw that his father in fact loved him, and so he sacrificed himself to save his father. I already forgot how it all happened but that's the gist of it. Apologies if this is all vague, and it doesn't help that I don't know when the book was published because I read it when I was in highschool but I bought the book at a bazaar. But the book looked really old.
The book was probably published in the 80s or 90s. Sorry I don't really bother looking at a book's publishing.