I feel so disrespected!!!

Okay ladies. So this is my rant for the night. I feel so disrespected and embaressed. I just need to get this off my chest. Okay, so my boyfriend has his own house. His house is literally back in the woods, no neighbors, very quiet and peaceful and I love it. Well before we started dating, his 18 yr old cousin and her husband used to live with him due to a rough time. They're back on their feet and have their own house now. They've been moved out long before me and my SO started dating. Soooo, earlier today things were getting a little "hot and heavy" while in the couch watching a movie. We were dressed, but we were fooling around. Well his fuckin cousin came busting through the door, stopped and said " are y'all doing it". I said no. She replied "good cause I don't wanna see that". Like wait a second.. If you didn't wanna see us having sex, then why the fuck did you come over without giving us a call or a text to let us know. She didn't even knock on the fucking door!! I should be able to walk around MY boyfriends house in my underwear. Or have sex wherever I want to with him in HIS house, without fear of getting caught. Just because you used to live here doesn't mean you do now. She came by to "look for a tee shirt". Nor did she even say hi to me after she busted in the door, and when she left... She walked out with the door wide open...!!!! I feel extremely disrespected and embaressed! I could only imagine how I'd feel if I was ass naked ontop of him or maybe going down on him. I told him he better say something to her, and if he chooses not to then I will. And i won't be so nice. Especially if it happens again. And I don't care if we're just makin dinner, cuddling on the couch, or sitting and talking. I will snap. Like take a step back, learn what respect is, learn how to be courteous and have some manners. Ugh I'm so pissed off!!