if you've already done the spell, and you're worried about karma, can't help you, it's been done. though if it's justified and you didn't go overboard with the spell, i doubt you'll receive any negative consequences.
to make sure you don't do it again though, i would try deep meditation to connect with your inner self, finding inner peace is a good step towards avoiding fruitless ventures like revenge. change the energy in a place would be a good idea, since some of the negativity from the spell or situation might still linger. have a cleansing bath, then cleanse your whole house with sage smudge. if you wish to cast a protection spell it would be a good idea, but it's up to you. i'm also not sure if you study feng shui at all [i don't] but changing the flow of energy could help as well. plus i've noticed occasionally rearranging the furniture in a space can make it seem new.