According to girls: Never, under ANY circumstance, should you attempt to date a guy who has dated one of your friends. It doesn't matter how long ago or how brief the relationship was. It doesn't even matter if your friend was the one to break it off, he is still off limits. You should barely even talk to him, let alone flirt with him or let him touch you where you pee.
According to guys: Dude, she's hot.