how to move on?

That sucks! I hope you said the whole detail about it. But to answer your question, the easiest way to move on is to think that you can move it. I know it would not be easy especially if you're on the situation but as for me, keep yourself on a positive side. Everything happens for a reason. If you really love him, you can fight for him but make sure that he loves you too because the hardest part of loving is fighting for someone who doesn't want to fight for you. Good luck!