How long to get over?

I was talking to this one man very briefly five years ago and I still cannot get him out of my mind. I still cry and my chest feels so heavy. I tried meeting other people, tried so hard to not think of him but I still cannot stop all the pain. I am stupid for still feeling so much for a person i knew 5 years ago. i am stupid and stuck. i just dont know how what yo do. i was in my late 20s and him in his early 30s