Edit: its my in laws house but we live here

Am i wrong for being mad that my mother in laws friend is having a party at their house, we have our own restroom in the back of the house with our room and living room. Everyone from the party is coming back here to throw up and use Our bathroom. I’m mad because i know no one else is going to clean it except me. It seems unfair that i have to clean up after their mess when my mother in law should be lending them her bathroom instead.