The worst pain imaginable is having someone that you love tell you that they dont want to see you anymore. I, personally, would rather have my legs amputated without anesthesia than go through this type of pain. Its happened to me, its happened to you and just about anyone else who has ever been fortunate enough to fall in love.
As you are sitting around with your heart feeling like its been ripped out of your chest and fried up with liver and bacon, like something Hannibal Lector would eat, people will be telling you the following:
You will get over it
He/She was no good for you
Time heals all wounds
Move on (my personal favorite)
It is his loss - you were way too good for him (or her, however the case may be).