I have a feeling that your relationship with this control freak of a girlfriend isn't going to last very long and when it's over you're going to want to have your friends for support and to help you vent and get over it all.
So: You sit your girlfriend down nice and you tell her that you will talk to your friends about interfering in yours and her's business but you will not be giving them up completely. You tell her if she walks out on you over you keeping good friends then so be it. Then you shut up and watch her back peddal to stay and work it out.
If she does indeed leave you then thank your lucky stars that you got out now.
Note: Please wrap up until you get to know a girl. I suspect if she wasn't preggers you'd be gone sooner rather than later.
“The willingness to accept responsibility for one’s own life is the source from which self-respect springs.” ~Joan Didion