Your peeping Tom might be violating a law, it depends on the state.
You may be the subject of a civil suit if Tom wasn't breaking the law, and you'll probably lose on the merits. (you did willfully damage someone else's property).
Now, if you were to fire a weapon containing ball bearings and the area downrange of your weapon was not known to be free of all persons; or if your municipality specifically forbids firing a weapon* within the municipal limits, then you are violating the law.
*self-defense in the presence of a bodily threat does not make it legal, but it is a valid and positive defense to such an action.
Note: in a civil society with laws when your rights are violated and except in the case of an emergency related to bodily harm or death you are required to report the violation and a court determines the responsible and/or injured party. In an uncivil society, you simply kill / maim /destroy those things which you don't like to don't approve of. This is not Lord of the Flies nor are you the judge, jury and executioner in all disputes with your neighbors.