Just move on and do things that interest you to keep your mind off him. Don't let him know how much you love or miss him. Of course, be respectful to them as you would want to be treated. He will eventually realize that you are doing well and respect that as well. Life's too short to dwell on someone who won't return their love. Good luck.
avoid him as much as you can. try not to be in his presence, but when it becomes necessary ignore them, find something to keep your mind busy. do not look at them deliberately and when your eyes fall on him, quickly look away. if he had treated you badly, then you should try to hate him for that. as you do all this keep looking for another guy. while this guy treats you like garbage another guy can sacrifice his life for you. the later is the best.