I know how you feel! My relationship ended this week although its been pretty much over since October. Like yours, i never really had a clean break. I sorta had to just 'work out' that it really had ended. Worse still, this relationship was one I went into quickly after my first had ended, and that is not good now, since the majority of reasons my first one ended are the reasons this one did too. It makes me questions all sort of things about myself and just generally dents my confidence. My boyfriend helped me get over my past relationship before we got together, and now its just all messed up for me in my head.
He wants to be very close friends, which i crave and find hard to handle both at once. I love him, and want him in my life in all possible ways, he's made me a lot stronger and beleive things about myself which i dont think i could do if he just walked away. He was my friend before we got together so we vowed frienship always, but its one of the hardest things. To try to make yourself fall out of love with someone that you still want to love and care for is so difficult. Its natural to want to hurt him/her, and in your case you seem to have much reason to want to hurt her. It really is your call on what is more important to you. Do you love her enough ( even just as a friend ) to want her to remain in your life in whatever way possible? Or do you feel wasted on her, like she doesnt appreciate you and in which case her out of your life wouldnt be much loss? Really you have to way up how much of a friend she is to you. If she isnt really a good friend at all then dont keep her in your life just because she is your ex and you were once so happy together. Its very hard as i know cos i am experiencing it just now, but we both have to realise the past isnt goin to come back. You know have to decide if she is worth it in your future. If your only hanging on for the sake of love and whats been then its not worth it.
Good luck. If you ever need to talk, im going through the same thing so might be able to offer some help or friendship.