Start watching a tv series,There's zoo many nice tv series.like ; how I met your mother, glee, gossip girl. Anything. It works. Just stay occupied. That way you don't tend to think about your new ex. :o Go out with your friends and family.
If you want you can start writing how you feel.. Trust me this is the second best way to help you forget all the memories... Every time you write something, you feel like it's not there in your head, the burden goes down, ur head and heart feels way too lighter. Keep pictures and all other memories away from your reach. Start doing something new, like learn a new instrument, learn how to cook, learn a new language, or anything you have been procrastinating for a while!
It does not get better with in a day or so, it takes time, but always remember that you are special and that it's the biggest mistake ur ex did, he/she will probably never find someone as good as you, n the world has 6 million people or so, trust me, it's not the end of the world, you are an amazing and beautiful person,pretty from the inside and out both, so just get your self together and get through it. God surely has someone better planned for you, at the end of the day everything happens for the best, and there is a reason for everything.