The last thing your boyfriend wants to think about is another guy having been with you. So it is best to try and keep what he knows about it to a minimum. Have you had a checkered sexual history that’s filled with lots of experience? If so, your boyfriend might have trouble dealing with this. If he cares about you then he will get over it.
First of all I am not saying to lie. If you have been with a lot of people then tell him. You have to be honest in a relationship or it will never work out. You can dance around the truth in the hopes that he won’t find out, but that will all be ruined the day he runs into an ex of yours. Just keep this in mind when he asks you a loaded question about your sex life. He has to love all of you even your past mistakes and decisions.
Don’t let someone else throw your past in your face or hold it against you. He must accept you for all that you are and that means everything. It doesn’t mean he has to like your sexual history, of course, but it means he can’t hold it against you. It’s completely unfair for him to want to date you and then start knit-picking about details from your past. If he’s constantly bringing up your past tell him flat out that he’s going to have to accept everything about you if he wants to date you. Let him know he has two choices accept that you have a past and let it go, or break up. If he cares about you at all, he will let it go.