I'm thinking of ghosting my boyfriend.
Why do you want to ghost him?
he was a terrible person
It can be tempting to just walk away from a relationship like this. It's still not good, tell them clearly it's over and move on.
Does not matter since i'm 40 and he is 18.
That is a big age different, but he still deserves to know why you are leaving. If he's young and won't care then there's no harm in telling him.