A Television show On BBC AMERICA?! I watched it a few yrs ago, a few of the seasons & can't remember the name!?

It was about i guess, the devil coming to earth, the antichrist or something and he got a girl pregnant and gave birth to a son taht would rule the earth and he grew up very quickly. they were at a school when this occured. her best friend was gay and she was killed but is still in the show (her ghost) i think I have only seen the first season and season 2 (part of it) it is killing me to know the name I really want to watch the rest..her gay best friend looked kind of like Kelly Osborne. not sure if it was her or not.