It's really hard to stop, and if you try you may actually cause harm to your own self. You must be certain before you do a black magick ritual on anyone.
Before and after the rituals of black magic, you must carefully purify your aura, as well as perform the ritual of returning curses, or additionally visualize a white-gold light and program your aura with affirmations so that it repels all the energies of the enemy that you did black magic on.