CONFESSION TIME: My girlfriend is no longer useful.

 I want to break up with my girlfriend. I started seeing her because she had lots of great books and revision materials for my upcoming exams. However, now as I have got all the materials I require from her and I am moving onto past papers to complete the revision cycle, she is no longer useful and is dead weight. Also she is very clingy. Any ideas on how I should break up with her? I want to get to the top and at this point she is becoming like a gangrenous limb holding me back, especially considering that I will soon be at university. SO my gf is no longer useful. want to break up with her, what should i do?