first off I don't think anyone knows "everything" about another. every person alive I think and this is just my opinion hon but I think everyone has something they never tell a spouse. you have been with him for 3 yrs I think you said? if you and he are happy I would leave it as it is. no need to give details of past relationships. especially if you know it would hurt him. I know it isn't easy. I have been in your spot. it is hard sometimes to figure out what we tell and what we don't tell. good luck in whatever you decide.