I would say this to Sheldon the next time he IM's you or emails you.
" Sheldon, DON'T EVER CONTACT ME AGAIN, this includes emails,
instant messages, phone calls, and in person visits.
If you continue to harrass me, I will be forced to go to the
Brick Township Police Department and pursue other action."
I just copied and pasted this to a female friend of mine who's getting harrassed by her EX.