Is it wrong to ignore an opportunity for vengeance when there will be no self-gratification, or harsh negative consequences?
The answers are entirely found in your own opinion and judgment. Only you can decide whatever you feel is best for you.
If someone hurts me then I hurt them back, usually immediately. I don't stew over the details. If I find myself having to think about it, chances are that I ask myself whether the person deserves punishment and whether or not it will escalate the situation.
If it really is that complex and difficult to decide upon then I suggest weighing all the pros and cons carefully and then choose to do what you think will be better for yourself in the long run.