This girl sounds like a total loser, and if you really love this dude, then what the heck? Go for it! If you've know your friend for a VERY long time, then it might be best to, actually, let her go and find friends who encourage you to do what you feel (Loose the friend even if you haven't know her for a VERY long time!). But if you think that this guy may just be the love of your life, but that you also REALLY want to keep your friend as a friend, than just be friends with the girl and a "Mega Friend" with the guy. I'm a dude, so maybe my advice is suckish, but that's kind of all I got...........
Wanna cupcake?