Ugh, why do I still have these feelings for her?

Ok me and my ex went out for about 4 months. I took her virginity for one also I was in love with her. I dont think she felt the same way about me. We till talk but she acts like she doesnt care about anythong that we went through which was alot. I cant get over her at all. We've been broken uo now for about 2 months and Im still not over her. I still think about her all day and have dreams about her.. I know its sad, if anyone can help me out I would appreciate it