You can't hold a man down without staying down with him. Maybe it's time to learn the language of 'let go'? It doesn't mean they are off the hook. It just means they are off YOUR hook and on to God's hook. I assure you God can handle them better than you ever could. You don't realize the energy wasted holding on to someone's offense. You think they are 'getting away' if you don't keep it at the forefront of your mind. They may seem to have gotten by, but with God they will never get away. If there is something you can do, focus your energy there. With what is out of your control, ask God to show you how to relax your grip, and let go.
Proverbs 26:27 - Good News Translation - People who set traps for others get caught themselves. People who start landslides get crushed.