Just ignore it as most people have said already. In fact, you don't even have to give them a reason why you are leaving, just hit the leave button. The chances of you seeing them people again are slim and by that time if you do see them again, they may not even remember you and via.
People can be harsh, that why I just take my leave and not say a word. And it not like they can't get another healer to replace you, they were only being retarded.