How can I tell them without getting mad?

My husband and I have just built a wonderful pool with all the accessories, its lovely. We had an opening party a couple weeks ago. Since that time my girlfriends want to come over all the time. My husband has told them we would like our privacy and when we want company we will invite them over. They still want to come. One actually told me last night on the phone something like wow you sure are keeping that pool to yourselves. I feel bad about not having them more often, but I love my privacy and never really had them over prior to the pool being built. Another reason for not having them is one drinks and doesn't know when to quit. Therefore, she doesn't know when to leave, which becomes an issue for me and my husband. He is not much of a partier. I am finding myself lying to them about my whereabouts. If I tell them I don't want them there I am sure our friendship will fade. Maybe thats what I really want anyway. Friends should not invite themselves. What would you do?