I'll try not to write a novel here but don't want to drip feed. DH and I don't have DC yet and we share a house with a close friend for financial reasons. The house is privately rented and we are joint tenants. Our housemate is normally a very nice person but recently we have been growing apart from her, primarily because she is social and enjoys having friends round regularly and going out clubbing while we are boring prefer peace and quiet.
She has recently made friends with a younger woman who visits regularly. Last night they went on a night out. Her friend came over before to get ready and I knew this friend was staying over after the club. When they left I was annoyed to find a white top I had accidentally left in the bathroom had somehow got smeared with red makeup and ruined. This turned out to be just the start. DH and I were asleep when they got back from the club but were rudely awoken by a man we don't know walking into our bedroom! I was upset, especially as I sleep naked! It turns out they had invited two men home from the club with them without letting us know. I'm not comfortable with having strangers in the house, as far as I know they had just met them that night. When DH and I went downstairs after the men left we found housemate's friend's used underwear on the floor in our living room, DH's CDs scattered, rubbish like cigarette packets lying around and our rabbit's cage open. The rabbit is nervous and we don't want drunk people handling her, also leaving the cage door open could have lead to her getting out and getting hurt but luckily she didn't.
Housemate's friend is 18 and still lives with her parents and I feel she is using our house to do things she wouldn't get away with at home. I wouldn't behave this way in someone else's home and it bothers me. AIBU to feel that this friend is taking the piss and my housemate is letting her get away with it? How should I address this?