My girlfriend was ually aulted last night and now she is acting strange towards me? read on plz?

i'm really p****d off! from what she told me last night. ok well she went out last night to a bar with some of her mates and their boyfriends, anyway I was meant to be going, but I cancelled, because I felt sick,, but anyway i told her to go anyway and enjoy herself. Well after they left, which was about 11.30, anyway she told me that her and friend left alone and went back to her friends car and as they were getting into their car some guys grabbed them both and started them with force and trying to pull her top down and jeans, but her mate was got punched by the other guy and luckily my gf didn't get beaten up. They called police and nothing has come of it yet, but my girlfriends mate, said that she thinks she recognised one of the guys and he has been taken into custody, but the other two (there were 3 of them) are no where to be found. I am so f****g angry about this and I really wanna go talk to this guy in jail and beat the s**t outta him and get him to tell me where the other 2 are, because i would literally kill them. I can't beieve this happened and now my gf is badly shaken, and she is scared to go outside. She was d 4 years when she was 17 and now this happens! She has really taken it bad and she is petrified to go outside even with me protecting her! last night she was up all night and i went in the bedroom and she was sitting with her back to the bed clutching her knees, just rocking back and forth. I just wanna do something, but she won't let me near her. Wtf is happening! I have booked her in to meet with a counsellor tomorrow.