Definently cut off contact with her, and don't beat yourself up over it, it's not worth it. It's gonna kill you for a while, but the best thing you can do is just keep yourself occupied until your urges to contact her go away, contact your friends and do stuff with them, or anytime you have an urge to call her or get lonely, go for a walk, go to the gym, go to the mall and treat yourself to something you've wanted... the message here is do SOMETHING, anything really to distract yourself. Everyone will keep telling you this and I know you probably think its bullshit at this point in time but its so true, it will get better with time.