I agree with red, leave things alone and it will sort itself out, she is probably very insecure given the age gap and the fact that you have known him longer.I wouldnt have been bitchy back though (your IQ comments and winding up all comes across as typical female bitching)
who knows if they may last, your comment on the longevity and the reason he is with her come across again as bitchy, who knows they may surprise you and you will have to start being nice to her for the sake of your friend.