People will only abuse you if you allow them to do so. Don't allow your "weakness" (which I'm guessing is absolutely nothing you couldn't overcome) to be something this creep can hold over you, because you are going to notify your true friends that he is stalking and harassing you. Print out his emails and take them to the police, and you can legitimately say to him that you've contacted the authorities. Then you block him and advise your friends to do the same, because if he will do it to you, he will do it to them, as well. Then you totally ignore him, and if necessary, get a restraining order against him so he knows you mean business.