ok...this is my suggestion:
tell her EX to stop trying...it will only hurt him more.
no point in saying anything about the guy from the first date because that was her choice and she will say "my ex didn't count...it was before my date...blah blah blah..."
frankly, i don't see how any of this should concern you...but if you're good friends with her...or any type of friend, tell her boyfriend to stop trying, because it will never work out (do not specify a reason), and also because if he doesn't stop...it might lead to both your room mate and her EX and her "current" to get hurt.
also...how old is your room mate? you said she slept with your godmother's brother...how much older would that make him? if it's like a 10 year age gap...i would definetly talk to her about it.
there isn't much point of taking to her because no matter what you say she will either say it's none of your business, or she will just listen to you and keep doing what she's doing. you talking to her will not make her stop.
but that's just my suggestion...your choice whether to listen to it or not. good luck.
