Advice on clingy friend?

I met my friend in college and we had a lot of things in common. She is also a year younger than me. Everything was fine at first, but when she had to transfer out of college, everything changed. I had to pick up on my life and move on while still being in contact with her. The difference between me and her was that I am not the type of person that constantly needs to talk on the phone nor need to hang out every single day. Well, I have been going through a lot with my sister's death a year ago, and while I am glad she was there for me at the funeral my friend did not call within the first two months after my sister''s death like all my other friends did. I feel as if she wants constant attention from me. Fast forward...a few months I originally planned for us to celebrate her bday, I was not able to do so because I had a senior capstone to do that contains intense research, and she knew about it. About two weeks before that it was MY bday and she asked when what I was doing, and I told her I was going to the club, and since she was 20 at the time, she could not come. She got upset with me and insinuated that I did not care about her bday at all. I offered to make it up to her and told her to come over so we can go out, but she never called me back nor let me know that she couldn't make it. I started distancing myself from her, and then she called and asked about me graduating as if she should know about it. FYI, I was not going to graduate because I have a few credits left so I wasn't able to and two, I would have told her and everyone that I was and I even told her about it. Am I being the one that is unattached or she is being clingy? I have a life of my own, other friends and family and plans for graduate school after I finish only one more semester of college. Should I distance myself or should I continue this friendship even though I told her before about her behavior?