letting him go

I was in love with him.I am in love with him.I can't let go even though the relationship has ended years ago .It was so easy for him to move on and be married so soon.My heart was broken.Is it because I DIDN'T TELL HIM I LOVED HIM.hE DID ASK ME A COUPLE OF TIMES. I WAS not sure.I am never sure of anything.So technically it is not his fault.But I think he knew I loved him but he did not wait .he moved on .oh so quick . Breaking my heart into million little pieces!Depression ensued and I suffered for so long.Why can't I let go  of this,after so much torture and suffering?I don't know.