You should ignore it. Do you know what Buddha used to tell for such. He used to just not accept it. That means just return it to them only if you do not react. For eg if someone tells You are a Donkey, most of us tell, I shall kick you. That means you are proving that you are one. But if you just keep quiet and do not respond, the person shall kick himself. At the end you are proving that he himself is a Donkey. THe same holds good for all such verbal abuses.