If you’re worried it will become a topic of conversation: you could tell your newer friends the truth before your closer friends arrive, or you could ask your closer friends not to talk about/share your sexual activity. I don’t think it’s anything to hide or be embarrassed about. But if you’re not comfortable sharing this type of information with newer friends, you don’t have to—and you can explain to your closer friends that you’re not comfortable with others knowing this about you.
(In the future, too, you don’t have to lie if you’re not comfortable sharing—you can simply tell people, “I don’t kiss and tell,” or “I’m not comfortable talking about this.” Those would be true statements that maintain your privacy.)