How to get over the best relationship you'll ever have in your life?

we broke up fom our 5 year relationship yesterday and i can't stop my self from thinkinking about him. i've tried going out keeping myself busy but nothing seems to work. it hurts so much. i have a constant worried feeling and it i feel like crying at all times i don't know what to do??? someone experienced this before, can you please tell me how i can cope, because at the moment i'm not. :(