i would say dont tell him but thats if YOU can learn to live with one mistake.
Because he'll feel that you have lied to him for all that time which you have , rather than feel you kept just ONE secret.
2 he will accept you, forgive you and go ahead with the wedding, BUT he will never forget what you've done.
Sometimes these hook ups happened before the bride and groom even knew each other, but others, right before the wedding.
I just want to confess what I did, tell him how much I love him and appologize but I'm scared.
A female reader, , writes 2 April 2012 : Personally, I think you have to tell him, and before you get married.