I used to be as loyal as they come. After two years of dealing with lies, I cheated on her.
Why did you cheat on her?
She was cheating on me first, so I returned the "favor".
Cheating on your partner is never an acceptable thing to do, even if they cheated on you. You guys should sit together and and sort out your issues. You are causing unnecessary pain to you, her, and other people by cheating.
I never want to hurt anyone but I feel happy about doing this.
You should feel bad since you are no better than her now. You should have jus ended things with her.