Welcome to Gaia! ::

This is from a psionic's point of view, and not a wiccan's, so bear that in mind.

But IF I were in your situation, I would probably send a psiball to subconsciously aggravate him about the situation. I also might make a sigil as the previous poster said.

EDIT: I should probably mention that the three-fold law also applies with psiballs and sigils. It's not going to be protecting you from the karma. I know you said you don't care but please consider quelling your anger and taking a different approach.

Resources:
Psiballs: (here)
sigils: (here)

Depending on how you define black magic, yes razz

Now, here's probably the best psychic defenese against such an individual that you're dealing with-based on my experiences, of course:

http://www.youtube.com/watch?v=T0-2lzA7_Cg&feature=related

(note: I do not own the song or video. It's just to bring lolz and prove a point)