Ask 1,000 people this question and you will get 1,000 different answers...Some guys will call you a wuss for having a heart that cares too much, some people will say they're sorry for you and advise you to try not to think about it (as if that's possible), and still others don't really know what to say.
I'll start off by telling you that I can appreciate this feeling - I've been there and felt that more times than I care to remember...I've taken advice from countless friends and relatives over the years, and believe it or not, "the best way to get over someone is [really] to get under someone else."
I know that sounds kinda shallow, but I swear it's the most effective (and the quickest cure)...See, here's what you have to understand: our hearts, our minds, and our souls are not initially able to withstand pain when it comes to affairs of the heart (any pain having to do with women) - we must condition ourselves to handle such pain through strength, courage, personal reflection, and most importantly, through the painful experiences themselves...
Think of it like weightlifting - at first it might be too hard for you to bench press 200lbs, but if you start with 50lbs and work at it consistently, never giving up, you'll increase not only your muscle mass, but your muscle strength, endurance, and threshold tolerance for pain...My point?...You can't lift the 200lbs if you can't lift the 50lbs...This breakup is your 200lbs - you cannot currently lift the burden of its weight...
What you should do is "get out there," as they say, and meet (and hang out with) AS MANY WOMEN AS POSSIBLE...I know, you're thinking "I don't want another woman," or some variation of that, but I assure you, if you hang with other girls you will be working your way up to fixing that 200lb problem...Let's equate it like this - say for every girl you hang out with, you get 10lbs closer to your goal of getting over the pain of your breakup...By the time you've hung out with 10 girls, you'll be halfway there...Once you've hung out with 20 girls, the pain of your breakup will be virtually gone.
Now, you'll never forget a girl - and anyone who suggests you try is foolish, especially if you really loved her...But that doesn't mean that you can't still get over her and move on with your life...Keep your memory of her in a very, very, very, small piece of your heart - that is ok...Even if you occasionally smile at the mere thought of her - that is healthy and totally normal...Just make sure there's plenty of room for all the success you'll have with women in the future (and with yourself in general) just by getting past this breakup now.
As soon as you get past this pain, you'll be much better equipped to handle more difficult pain (of any nature, regarding women or not)...Any questions or comments, feel free to get back to me...I feel your pain, man - good luck!