This is gonna be a long one, so I'll put a tl:dr at the bottom

So for the backstory, my mother was incredibly abusive towards me and my sister during our childhood, physical abuse, emotional abuse, you name it, she did it. My father tried to get it to stop, but he's too nice, and he's getting old.

When I hit the age of 14, she left my father, and I couldn't be happier. She moved out, and was completely out of our lives.

3 years ago however, my father let her move back in with us, even after going through an official divorce procedure and everything. And it seems like she hasn't changed at all.

She still acts cold towards me, and toxic as well. Last year I had the honor of hearing her say to my face that she wishes she never had me. Fair enough, I tell my father, and he constantly threatens to kick her out if she continues with her behavior, but he never does anything. Also, she only acts this way towards me when my father is not around, cause she knows that she'll get fussed at if she acts this way with him around.

She currently looks after him. By that I mean she'll cook him dinner, iron out his clothes, and clean somewhat. Meaning a mess could be in front of her face and she wouldn't get to it until hours and hours later, despite doing nothing but lying down on a couch, and playing on her laptop. 

Onto my younger sister, she has a terrible drug problem. She'll do drugs even though my father clearly stated that the moment you do illegal drugs, he's done with you, he will not help you out of any bind if you willingly mess with drugs like that. In addition, she has him and my mother take her to work, and she has the gall to wake up me and my mother at 1 or 2 in the morning to take her to get drugs. She only does it when my father is not around, because she knows that she'll get in trouble if he is around. Oh, and she doesn't contribute to the household whatsoever, and has the gall to yell and fuss at them and get into arguments when they rightfully tell her she needs to stop doing drugs. 

They offered and set up a meeting with a hospital that would supposedly help her with her addiction. She didn't go, instead she went to her boyfriends house and did more drugs there.

Now, I probably should've talked to them about all of this, right? Well I cant. The moment I bring up any of their problems, they immediately get very hostile, and very defensive, constantly beating you down with insults and goalposts moving all the while not listening to me. So that's out.

Recently I learned from my older sister that my father plans on leaving the house in her name. And she's told me that she plans on leaving the house in my name once it's in hers. My sister nor mother know this, and I've made sure I haven't told them about this. Now my older sister is fantastic, we bond over dinner whenever she visits us from florida. She also dislikes my younger sister, and doesn't care too much for my mother.

I've tried to move out a number of times. But my father is getting old as I've said (he's currently 66)  and he'll actually break down into tears and beg me not to go, and that he needs me. I've obliged, and at this point I give him rent, and pay for everything I use. All he provides for me is a roof essentially. 

So basically, when my father passes, I want to kick both my mother and sister out of my house.

WIBTA here?

Tl:dr put up with abusive mother for years. She leaves for years, and comes back still toxic as ever, my younger sister abuses my dad's love and takes full advantage of him by disrespecting him, and doing drugs in his house, my father is leaving the title of the house in my older sisters name, which will essentially be in my name, and I want to evict both of them the moment the house is in my name.