Okay so, naturally

Cheating is a natural event between living mammalians . It should not be frowned upon, like how the homo sapien society does these days. We see fellow animals doing this in nature all the time, and we should be no different since we're also animals. Yes, we are far more sophisticated, but do not forget our origins, rules limit us. Your act of cheating is an act of nature. Do not feel bad.

Okay so, critically

You're stupid. How could you be oblivious to prudence? How could you of not thought before hand, and realized that it would be a bad idea that could have residual affects? Now you feel sorry? Complete display of hypocrisy and ignorance.

Okay so, euphemism

It's okay. I'm glad you owned up to it and realized it was a wrong thing to do. You can tell your girlfriend and explain, she'll understand. Just promise to never to it again.

Okay so, reality

She's gonna dump you. Cheated once, probable to cheat again. If she has self respect, she'll leave you.