Most Helpful Guy
I'm partially plagiarizing the last opinion I just posted to another question, but the answer (IMO) is the same...
You discovered that the relationship you were in was not the right one, and it sucks. There's not much that can be said to make this less painful than it is, but give it time. Not only does the sting wear off, but you will recreate your life with new friends, and eventually a new boyfriend, and things will be better than they ever were before. You will be able to look back and think to yourself "Wow, that hurt at the time but it turned out to be a blessing in disguise!"
Life has it's ups and downs, this is a big downer but don't let it destroy you. Move on from it and look towards the future with your head up and eventually a smile on your face. Learn from it, and don't dwell on it.
Get busy with activities and friends... Use some of the free time you have now to get a gym membership and start working out or start volunteering at an animal shelter, spend more time with friends who you haven't been spending as much time with as you used to and start building new friendships with new people from work or school or other social circles...
What you want to avoid is idle time. Moping around for the rest of time isn't going to bring you ANY happiness, and the sooner dust yourself off and move on with your life the sooner the pain you're feeling now will go away and the sooner you'll be back to truly happy.
Keep moving forward! You can move on. One step, one day at a time! :-)
Most Helpful Girl
I won't say forget about him, but what helped me (I never was in a n relationship but I was hurt a lot) is to distance yourself from him (it worked for me as I'd ask them out on the last day of school so I had months to recover and not see them). Do what you want to do, do fun things that won't remind you of him. Go out with your friends on movies and just girl nights. Go to a gym and exercise with music (that doesn't remind you of him) and/or learn a martial art. Do things that won't make you remember him, but since you were with him for 4 years, it may be hard. Just know that the best way to get over something is to distance yourself until its just another thing to get over.
In a way, we want things we can't have, but after awhile we will want something else and forget after longing for it for too long. So in context, you wish for him now, but as the breakup goes on for a longer period without seeing much of him, you will soon forget your heartache. You may even find someone else. And that's something you should do after you know for sure your over him. If someone says date someone else just to forget him, it won't work as you still have feelings for him and it won't be fair to the person you date after him when the only thing you see him as is your ex-boyfriend.