HOW DO I LET GO OF THE MAN I LOVE, WHEN I KNOW HE IS THE ONE?

I BROKE UP WITH A MAN 2 YEARS AGO, TRIED TO GET HIM BACK LAST YEAR. HE GOT MARRIED 3 MONTHS AGO. I CAN'T GET HIM OUT OF MY HEAD. I KNOW HE WAS MY TRUE LOVE. HOW DO I GET THIS MAN OUT OF MY HEAD.