Why do i feel this way?

Not too long ago i broke up with muy boyfriend and i was completely and utterly heartbroken. I cried for days and it felt like my heart was so faar beyond repair. I wanted despertely to get him back but i never tried... well i went on a vacation for a bit and when i returned i no longer felt this way. I couldn't stand him. I didn't want to be in the same room as him, or hear him talking, or anything like that. Why do i feel this way? Is it because i am over him? Or is it something else? And how can i be his friend if i cant stand to be in the same room as him? Please help... i dont want our friendship...