AITJ for putting hair removal cream in my conditioner for my sister in law to use?

I (15F) hate my sister in law (31F). There was a whole thing with her and my brother (her husband) but I won’t go into detail. My brother sent her back to her home country after a big altercation happened between them and she lived there for a couple months with her child (my niece). My mum felt bad for my niece because our home country is not really safe and most of the people there are living in poverty so she told my brother to make them come back to where we are so that she was safe. My brother agreed his wife and my niece came back but he doesn’t want them to live with him but he wants them to live with us. They came back and don’t get me wrong I love my niece but my sister in law thinks that I’m the one who should be taking care of her all the time because it’s “giving her a break” but all she does is sit on her phone all day and lay in bed and me and my family have to take care of my niece. Ever since she moved in with us, I’ve noticed my stuff gone missing or is running out and it’s because of her, I mean she could just of just asked me if she wanted something? She always wants to join into my conversations which are none of her business and always barging into my room like have you ever heard of privacy. She doesn’t know how to properly wash dishes as well and everything she washes always is still dirty after and it’s really annoying because I have to wash everything again. I don’t think she has any commonsense as well cause my niece is still a baby and can make mess sometimes but when she makes a mess, my sister in law doesn’t even bother to clean it up she just stares at it and expects me or my mum to clean it up like what? You’re her mother!!! Even in public when my niece makes a mess I get second hand embarrassment because again she doesn’t clean it up and expects someone else to do it she’s such a bad mother. As I said before, she kept on using my stuff and I got really pissed at the fact she was using MY expensive conditioner and it ran out so I put hair remover cream into the empty bottle of conditioner so that she can use it.