I can only validate your experience as everyone else has pretty much done already.
Good boundaries start with assertive communication. First rule is to use I statements, and second rule - you don't have to explain anything - third is to say what you mean and mean what you say so follow through. He will get the hang of it and figure out how to respond. It really does work.
It will help you sort out what you need/want and allow a balanced response from you and peace.