history: I just discovered that my girlfriend had been sleeping with my best friend. It's infuriating to know that she did that behind my back I just discovered that my girlfriend had been sleeping with my best friend That's terrible!  How did you find out?
current: My friend confessed which, I give kudos for, but he knows what he did. It doesn't make it ok
next: It's hard to find forgiveness for something like that.  Still it's better that he confessed than you having to find out otherwise.  If only a little better/