FIRST: I wasn't sure where this went, so i just put it in here, im sorry if its in the wrong place.

A person who i once donated to on the web is threatning to send letters to fellow members of my family and call them, im scared of this, i don't want him calling them up, he is refusing to stand down on the matter, I'm really worried, i don't even know him, what can i do? If anything?