My S/O’s mom refuses to put on clothes in our house!!

Sooo, my S/O and i have been together for 10yrs now. We’ve lived together for quite some time. Well, about 3 yrs ago he buys a house and randomly says that him mom and little brother(who is now 20) would be staying with us for a little while until she gets back on her feet. I’m like, ok cool. Fast forward to today, i am so fucking miserable. Neither one of them have a job. Just me and my SO. She walks around the house naked af/ just underwear nthn else and so does the little brother. They have NO respect for our privacy, especially mine. My SO works in the oilfield so he’s gone 2.5 weeks out of the month and it is the absolute worst. His mom is passive aggressive af like it’s her fucking house. Has all types of people over. His brother walks into our room while I’m getting dressed or butt ass naked just because he thought i wasn’t home. He’s filthy as fuck. Eats all of the food that i BUY for us and doesn’t even try to replace it. I’m weirded the fuck out and I’m angry. Out of respect, i haven’t really said anything bc i can get real rude when i feel backed into a corner and it is his mom but i am FED UP. I’m really ready to move out myself and let them all have it. Help what should i do!? I’ve told him i don’t feel comfortable but he just thinks it’s no big deal and that I’m acting antisocial. I feel like they are taking advantage of the free ride. I use every excuse not to go home but now i am just emotionally tired. I shouldn’t have to feel this way every single day. Idk what to do besides leave. :(