My man flirts with women in public and it's making sick!?

He tries to make u feel bad by saying that ur insecure and that he will stop going out with u etc but by the sounds of things it's obv that he's just a dog! Next time it happens confront him and if he says the same stuff again, flip it on him, say that if he carries on then u'll leave him and see what he has to say? I would not tolerate my bf checking other girls out etc. Sure he looks at other girls but it doesn't mean anything. But nodding his approval at them? That's beyond a joke!