What to do Boyfriend has REALLY bad breath?

My Bf has terrible oral hygiene, even after brushing his teeth it smells awful, he is very affectionate and wants to kiss me all the time, but I cant help but play it off and back away, it really turns me off and makes me not want to have him anywhere near me, I try to kiss him back but he breaths all his bad breath is just on me.... ewww its so nasty, and he gets sad he says " why dont u ever want to kiss me, I just want make out with you".... what to do guys? I dont want to be rude, as he is really sensitive... Sometimes Ill offer him guy but the bad breath still wont go away :/