one-side love

how to success the one-side love.my situation is she reject my proposal.My problem is that.. even though I am trying to FORGET her.. I can't do so,I really can't.. it seems impossible for me to do this!! Every time I see her in my classroom.I think I can't live without her but I also know that she is unreachable... this feeling of helplessness is just killing me... plzzz can anyone help?? wht to do plzz advice??****