Every so often I question why I went after him so hard, why I used all my resources, and didn’t just “let it go.”

This man was more than just a troll. His actions against you, your family, and your colleagues were criminal. You acted in the service of bringing a criminal to justice.

These facts probably won’t do much to assuage any guilt you may feel, but morally, your actions are entirely justifiable, even commendable.