I'm cheating on my wife
Why would you do something as horrible as cheat on your wife?
I'm not really cheating on my wife, she's cheating on me so I'm just taking revenge.
It's wrong of her to cheat on you. It's also wrong of you to do the same.
It's okay as long as it makes her feel worse.
Cheating is cheating regardless if you feel it is justified. It sounds like your relationship is a mess. You two should probably talk things out or even start plans to end your relationship.