@ZAQWSXCDE,
How? Slowly, a little at a time. Each day, in fact in every second you will move forward taking tiny almost shuffling steps at first, then bigger and more confident strides as you meet new people (not necessarily of a romantic nature) and take part in new experiences. After some time has passed you'll notice your smile and laugh have returned.
Life shall go on, stay strong and maintain the positive nature within you.
Sure enough you may remember him; yet, he won't encumber your every moment any more.