[Miranda_]

Exactly this. The only time that I'd say to date a friend's ex would be a) if they parted on good terms, b) she's fine with it and c) a considerable amount of time passed since their breakup. A guy who makes a play for his ex's friend a short time after splitting with his girlf, especially if he cheated on her and treated her badly, should be labled trouble with a capital t and avoided.