Depends on who dumped whom.The "dumpee" will always have difficult time to recover. You need to find a closure and move on. Feel sorry will NOT help you to recover and forget.
Be strong and you need to find a way to FEEL and ACT like "winner" coming out of this. Then you will feel better faster. Whaterever it takes. Find a better pastime or spending more time with friends in school and do better on course. Whatever regular things that make you feel a winner.
Next time, make sure you are not the dumpee. Once you find the relationship is heading down, be pre-emptive!!! (Sorry ladies... I am just trying to help this brother.)