The reality is that it's pretty much just time that heals this pain, and it can be a long process. But you can make it easier by keeping busy to make that time appear to go more quickly. Take up a new hobby, go out with friends, watch a film or just go for a walk and force yourself to think about positive things. Instead of dwelling on things you wanted to do with your partner in the future, think of things that you can do.
I really struggled with a break up years ago, and one thing I found helped was to go outside and just look up at the sky on a nice day - there's something really heart-warming about looking up at the sun and a blue sky.
The worst thing is to sit dwelling on it for too long, however you should allow yourself some time to be upset, think about it and process it - but try to set yourself a time to do this, and force yourself to do something else afterwards to take your mind off it.
Also with my last breakup, I found keeping a diary useful as it gave me an indication of how far I'd moved on. I've just read the one I wrote 6 months ago when I was dumped by my girlfriend of almost 8 years, and the day after we broke up, I cried solidly for 1-2 hours - it wasn't even crying, it was whole-body sobbing that physically hurt. I've never felt pain like it. But just weeks later, I felt generally OK. Not 100% over it, but actually happy for the majority of the time.
You will get there - everyone does - even if it doesn't feel like it right this moment.