Spells, rituals and other products of one's personal time and energy, are subject to your concurrent wavelengths of energy. During the first event, you wanted it to happen and the intent was there to make it happen.
Though with the result seen, more than likely, the following result is going to happen in one of two ways.
The first is that the spell will simply nullify itself by universal command. Spells that are specifically meant to be based on your energy and the mindset of another person, generally depend on the status of both being unchanged. If they've truly changed, their karmic field will not be different from what is intended and they will, most likely, no longer be harassed by the spell, because the situation has changed.
In essence, because the energy has changed, so too has the purpose and the idea behind it. Curses tend to only affect people that the universe knows, in essence, deserves the curse based on your intent when you made the spell. Because they have changed, it's no longer valid in a sense and should vanish in a sense.
The second way this could go, is that this energy is returned to it's sender in the same way it was formed. The karmic balance now exacting a price on it's sender that may or may not be noticeable in the current time frame you're experiencing.
In either case, it is best to meditate and let your energy recede to the universe. Let your intent be known that you no longer desire the person or yourself to come to undo harm and that you wish only to put out positive and recieve positive. It is best this way, so that if something does occur to you or them, the blow may be softened or ignored altogether, or procure some form of benefit the universe deems desirable for your state.
I hope this was helpful and that all is well in your endeavors. I'd recommend in the future not casting such spells as they have potentially very negative side-effects, but that is your own path and beliefs, so I do not want to sound like I'm trying to lecture you. I just don't see it as worth it.