I agree with P&R Mom ~ your feelings are totally normal.
You are probably in love with her, and feelings cannot just be turned off & on, yet you feel that you have lost her, so you are grieving. On the other hand, you are not entirely sure how she feels, so you are confused, and on top of that, you feel used and betrayed. It is not surprising that you feel bad.
However, this is not an uncommon scenario at your age. People change and relationships are affected. Emotions are heightened, so responses are particularly painful.
Time heals. It's true.
No matter how awful you feel, you know, deep down, that you do not want to be in a relationship, unless you are in love with her, and she is in love with you. You don't just want 'a friend' ~ and, really, you don't just want 'a rebound'. In time, you will find a girl who knows what she wants ~ and it will be you. Hopefully, you will feel the same way about her.
I'm sorry, but I don't know what age freshmen and sophomores are, but I can guess late teens or early 20s. As I said before, these romances can work. I met my husband in college and we are now in our 50s. For most people, though, they don't last. They are part of the joys ~ and pain ~ of youth.
Give yourself time.
