Often people say they understand, or say 'Ok', when they honestly have no idea. It could be indeed that he simply said he's fine with it, but didn't know fully at the time what you meant (and probably still doesn't understand.
It seems a bit odd that you have asked him to break up with you. You think he's rude and not understanding of the situation. You are want to break-up, because he's being rude and whatnot. Even after you have talked to him about it, he still continues to act in the way that he does.
It sounds like a good idea that you send him a message. Keep it neutral, leave emotions out of the message, and then block him if you feel that's best