Thanks Argo.
You can't cure a broken heart in a day (or twenty). Listening to sad music helps, if you're the crying-it-all-out type. I would suggest not isolating yourself from friends, because as much as you don't feel like doing anything with them, once they're there, they're surprisingly effective on cheering you up.
It's been awhile since someone broke my heart, but when it happened, all I did for a couple of days was just sulk at school and cry my eyes out at home. I thought it would never end, but after a week or so, the hurt started going away, and I ended up forgetting about him completely without even realising it.
Try not to think about all the good times you had. They're heart-stabbing knives.
Watching DVDs (just not really romantic ones) helps you escape your own life.