Revenge against someone who feels nothing for you is pointless.IMHO its just a consequence. If gf stole from his bank account and he pressed charges and saw it thru to justice thats a consequence. Its the same as providing some pain or to stop supporting someone that hurt you badly.
It shouldnt be done as "revenge" but if you want to enact a consequence great.
And in the black magic world of "power" getting cheated on and complaining but staying gives her empowerment at expense of your pain and degredation. Cheaters need to be cheated on. Often they have no clue until its done to them. So we spank our children or we punish and we still love them. So do whatever you choose to do. Just dont do it as "revenge"
It's like kicking a steel pole and expecting it to be hurt when it's ur own leg that gets bruised.