If not, then you need to.
And if that doesn't improve the situation, then you tell your friend you're concerned about things she has said. You ask if you're reading things correctly. You listen to his answer.
Then you give the girlfriend extra chances to show you why your close friend likes her.
In the meantime, your party will happen, so invite her despite your reservations because that's what close friends do.
Then, if you've dealt with her directly; taken your concerns to your friend; granted the girlfriend extra chances to win you over; invited her to your event(s); and yet she's still mistreating you or others, then you get to say to your friend, "I'm in a bad spot because you're one of my closest friends, but Meanie has said awful things to so much of my guest list that she's no longer welcome at things I host."
E-mail Carolyn at firstname.lastname@example.org, follow her on Facebook at www.facebook.com/carolyn.hax or chat with her online at noon Fridays at www.washingtonpost.com.