I think I am in depression. Out of fear.

My girlfriend is getting married to someone else after a five year relationship. And I am hurting inside every second. She met me twice after the marriage got fixed and when I confronted her about how she left me, she said sorry ! I have an important exam in one month. I am unable to study. I am unable to focus or be happy. I feel betrayed. She is about to get married in fifteen days. I don't know what to do. She is meeting me casually In the mean time and talking to me also .I can't be with her I can't be without her. It seems like my reality is crashing. I don't know what to do. I am feeling helpless, it's like my emotions are controlling me. She says that she loves me but she is getting married to the guy out of fear.