What!?! Are you fucking serious? Her honesty? The bitch is screwing around on her fiance, and you applaud her honesty? Get real! And on top of it, you're cool with being the douchebag "other guy?" Have some respect for yourself, man. Cheating is bullshit. Unless they're in an open relationship and he's cool with his lady getting her meat pounded, then you are both shitting all over each other's consciences and being total assholes.
Sorry to be severe, but you brought it up, and that's my response. Find a chick who is actually free to have fun. Respect yourself enough to have a chick, even if she is just a fuck buddy, who is doing you for you and not using your cock as a stand-in for the guy she really wishes she was fucking at the moment. Whores are cool and all, but not not when they're also scheming cunts.