So wait...when your ex, was not your ex, you had sex with her even though things weren't lookin' good?

And your current girlfriend has issues with you having had sex with your ex-girlfriend, when she wasn't your ex at the time?

Is that correct?

'Cause if that's the case, your new girlfriend is an insecure whackjob with no sense of logic.

Who cares if you **** your girlfriend after an argument, since when was that "immoral"?

It sounds to me like you have a new manipulative bitch on your hands. I say run.