I'm going to be frank: I'm a cheater and I don't feel guilty.
How do you justify that?
I've been doing this for awhile. I can't control myself.
You shouldn't cheat on someone you care about. Unless you don't care about them then you should break up with them instead.
It's not my fault I have needs. People have needs.
Your partner has needs, too -- she needs to feel safe and loved. Your cavalier behavior is the opposite that. If you're unable to be faithful, you should sit down and explain that you're not ready for a relationship.