Personally, if I had that turn of events occur to me, I would be inclined to cease any non-vital communication with her or her gorrillas, and just remember that if you didn't try to rape her, then you didn't try to rape her.
If you have any Police contact (which I personally doubt if things happened like you said above ~ this appears to just be a bully, stick-up-for-mates tactic), then just maintain what happened and stick to the truth. You mentioned dorm room so I'm guessing Uni? Do you have any campus-linked Police (I hear of them often); if things go further, more threats for example, it may be worth having a chat to them??
Not sure of your particular circumstances, but it may also be a good idea to have a chat to your parents/guardians if this goes *any* further just so that they can help and support you.
But as above, stay away from them as much as possible. I would think that if you don't hear from them again very soon that it was just a threat from them to stay away from her.