It's the principal who really needs to question himself, not you. Sure you're all consenting adults now but it was his position of trust and responsibility for your welfare as a child that brought you together. I doubt his fantasies for you or other boys conveniently started the moment you left school; that he acts on his fantasies shows, for me, lack of self control and of integrity. He is taking advantage of his special access to young guys to get laid. I would stay away from him as he is taking advantage of you.