I need help,

I am extremely happy with my relationship, i getting married next year to an amazing woman. But.... im have dreams of someone else, and old friend who, yes, i liked, but kept it to myself and didnt go for it.

What should i do!? I love my fiancé but this person is invaiding my mind. Should i tell the friend? Tell my fiance? I dont know what to do, its driving me insane.