These girls sound toxic. They'd rather hang out with you and your friends and put down the things you guys enjoy instead of finding something for themselves to enjoy. That kind of negativity feeds itself, and that kind of person doesn't change overnight (nor is it your duty to try and change them). You've learned a lot about yourself and where your interests lie, and if you feel you would have to suppress your interests for fear of being mocked, then living with these girls is a step in the wrong direction.
I say go your own way now. Do it respectfully, but make your reasons clear - that you can't live with people who are going to disrespect you for the things you enjoy and who you are. Being nerdy is nothing to be ashamed of; shaming people for their interests is. You said you have a few friends who need roommates - room with them! It's pretty fucking great living with people who share your interests. And your friend's situation is no longer what it was. You were going to room with her because she didn't have anyone to live with, but now she does.