Re: How can I forgive and move on
"I know my love is desperate and obsessive"
It sounds as if you don't know much about relationships so let me start with this: one very basic (but difficult) fact about relationships is that if you ever want a healthy one, you much be healthy by yourself. The fact that you feel desperate and obsessive towards this girl will driver her away. People are drawn to strength and confidence. I'm guessing that once you two started dating, it became clear very quickly that you would cling to her and she cut you off before things could get really ugly. I know: I've been that girl. If you're friends, the thing she probably regrets the very most is hurting you and losing the friendship but she probably also can sense that if the desperate and obsessive "love" continues, pain down the road is far far greater.
Maybe this perspective can help you forgive. As for getting over it, that is far more difficult since it looks like you have bigger things to work through personally before being able to deal with a relationship in a healthy way. I strongly encourage you to do so, however. Wisdom comes in increments and it will take work to become a person fit for a relationship but it is worth it! Also, if you do not, eventually you'll find yourself in an obsessive "love" relationship that is very dysfunctional - perhaps the girl that sticks around will be a codependent one who thinks she can fix you when she can't, or worse, one that uses you since she sees you are obsessed. This could really hurt - I've seen it before.
I really hope you do take this advice to heart. You do sound like a decent person as most people are, just not ready for a relationship. People that go into relationships anyway end up jaded and bitter, but I can tell you that there is such thing as true love and a beautiful relationship, IF the two people are whole FIRST.
Good luck.