I've always found that the best way to deal with things is to simply move on mentally - I know, easier said than done, but I just approach it as making the decision and then sticking with it. It always feels like a huge deal at the time, but it's amazing how some space and a few weeks can wipe the slate clean. A large percentage of the attachment of a relationship of any length is the familiarity and routine of interacting with the other person, but this doesn't take long to let go of. The emotional aspect is mroe difficult, but again, sometimes the spearation can give you a fresh perspective on the person and you do realize that you're better off without them.
If you allow things to get 'dramatic,' as they say, with repeated contact, emails, whatever, then it will all just take longer and frankly the odds are that you won't find your relations with that person to be improved by this sort of thing. Whenever I've allowed this to happen its eventually just become an annoyance and dragged out the inevitible. Plus, if yo have some psuedo-girlfriend
hanging around and calling, it can be a real bitch when you meet somebody new that interests you.
Everybody has a different strategy for getting their mind off things when a relationship first ends. If I'm feeling bad about something, I usually just focus on work or a project and it seems to really help. Other guys I know do hit the rebound circuit and swear by just fucking a few random women to clear thier heads, although I never really understood why this was such a great option - it seems more like some sort of juvenile revenge thing, but I try not to judge. I know somebody else that like to take a vacation or travel somewhere new. Exercise and fitness is another thing that's a healthy and convenient time filler if you need some distractions.
So, I suppose my advice is to make the break clean and be confident in your decision, and then find something that you enjoy or keeps you busy if you find yourself having a hard time. Best of luck.