Most Helpful Girl
You need to keep busy. I think the problem is your mind is allowed to wander and start thinking about her. Try to remind yourself of why it didn't work out and focus on the positives. Focus on the fresh start you get now. Think about the things you didn't like about your girlfriend and be grateful that you no longer have those barriers in your life. I know that sounds really mean to think that way. But I've dated guys who didn't like specific foods, and I love food. And so when we were no longer together, I could now indulge in those foods without hearing complaints.
It's nice sometimes to have the freedom to do things you wouldn't otherwise have gotten to do. Go out, reconnect with some old friends and make new friends. Join a club, invest in yourself, get a haircut, buy some new clothes, take yourself on a trip. Do things that heal your soul.
Break ups are tough and it's okay to be hurting through a break up. But the best thing you can do is to grieve and try to move on. It's not the end of the world, even though it definitely feels like it. You will get over her, like you have gotten over others in the past. It will pass! And you will start to feel renewed! :)1