What should i do,i cant define how am feeling towards my ex-boyfriend?

i broke up with my boyfriend three weeks ago,and since then and am feeling nothing at all.i don't hate him not at all.in the same time i feel am not loving him as before.during all this time and am searching inside what do i feel towards him,but no answer.im so much tired and nervous because i cant define my feelings at all.since we broke up and he z trying to return me back and he loves me so much and i used to love him.and when he tells me how much he misses me,am not feeling him.am not feeling his pain.now we agreed to stop the relation till we graduate from collage which means after four years then we can marry.aah please i need help,i wanna know why am not feeling anything.