Forbidden loves are often the ones that draw us the most strongly. It hardly matters whether you've had a relationship in a physical sense or not--anyone who's occupied your desires this completely is someone you've been in a relationship with ... even if he hasn't been in a relationship with you.
If in fact you didn't dream about him last night, that would be good. It's much harder to break off with this sort of involvement, because you don't see this fellow as a real guy with problems and weaknesses.
We can direct our dreams if we focus on them. Try images of sending him away from you, out of your home, locking him out (& meaning it) before going to sleep. Replay dreams in which he's appeared, and change them by making him leave those dreams.
Just a suggestion. They won't work though unless you truly want him out of your life and mind.