I want to try it just once
What do you want to try?
I once tried to rape a girl friend. We were both drunk that night and I had unprotected sex with her
It's not good to try and rape anyone, and consent is very important for both parties in a sexual relationship. Abstain from your urges and try to seek help if you have more of them.
I don't see why it's a big deal? I only did it once and I didn't even complete it. I don't have a big history of it.
Even one time is too many times. Rape is an awful, violent action that is abhorrent. You should apologize to the woman you attempted to rape, but don't be surprised if she doesn't want to speak with you.