You can do something cathartic. After getting dumped, I once pushed a tree down in my back garden and carried it around to the front of the house for disposal. My muscles ached and I was cut and bruised but felt a lot better afterwards. Other times I've just gone out drinking with friends. There are sater more controlled ways of doing it - try exercising to exhaustion, get away for the weekend and GI hiking, drive a tank, go to one of those places where you can smash things up, organise a big paintballing session, etc. Something that breaks you out of your routine, preferably gets you out of your local area, needs all your focus and tires you out. It should take your mind off things, get you so focused and tired you aren't brooding about it and provide a symbolic break so you can leave your baggage behind on the other side.

It's not an instant cure, this will all take time but it's a decisive first step.