I don't know that you'd have to tell him how long you've been drinking, just that you're concerned with the hold alcohol has on you and want to stop. If he really loves you don't you think he'd want you to be healthy?
I was embarrassed to death to tell my family I was an alcoholic. But I did, and I got over the shame. They love me and only want me to be healthy and happy. I hope it would be the same for you and your fiance.
