I accidentally cheated on my ex and lied about it.
Was this a one-time fling or do you plan to persist?
We already have plans to do it again. It felt so good I don't care.
Everyone is sometimes attracted to other people, but it's not OK to act on it when you're in a relationship. You need to make a choice out of respect for your girlfriend.
Good idea, but I'm not going to tell her.
Cheating on your girlfriend is wrong and harmful. If you're not going to tell her what you did, then you should at least break up with her. Staying with her while cheating on her will just cause her more pain down the road.