Getting over someone

How am i supposed to get over a girl that i love deeply?? It did not workout between us for reasons out of my control , ever since breaking it off i can't stop thinking about her. I miss her immensely i have not eaten for the past three days, just remembering her makes my chest physically tight. I have been crying at random intervals for the past three days. I cant work, i cant speak everything feels horrible. Someone tell me, how am i supposed to function like this??