I really miss my now sadly ex-girlfriend....how do I let go?

I don't really want to, I spend stupid amounts of time pouring over our pictures and thinking about her. I made a real effort to find a replacment since graduating from uni or doing things to make me forget, but she keeps creeping back in! She doesn't seem to miss me and that hurts. I have recieved zero phone calls from her and she refuses to reply to my e-mails so I have just let it be. I don't wanna har her, but privately she meant the world to me. I never saw her at our leavers ball because I was struck down with shingles and I was hurt because she never called or checked on how I was until before graduation. At graduation (we live miles away, but always made an effort to see each other.....she lives in skipton.....me in Hertfordshire), it was like old times and she looked stunning. Now everything is gone.....no real goodbye.....just cold.....I really find it hard to concentrate on anything else but her...I feel a bit bitter and rather used. She was def more popular than me!