AITH for refusing to reserve my building's event salon for my half sister after what her mother (not mine) did to me?
Hello Reddit, I have kind of a situation here. I (32,M) arrived to my current hometown (Not in the USA) 1 year ago to search for new job opportunities and just, starting over, because I had many emotional issues in my last city. I had to leave friends, my bf (but we still keep in contact and visits) but it was necessary. I had to stay with my dad (79) for a while, but our relationship is not good. If I had another person to rely on, I would have gone for them, but my father was the only option.
I seriously consider him to be narcissistic, a liar and just not pleasant to be with. He would leave the bathrooms dirty, he would berate me for not being a doctor like he is and while he's not direct about it, I know he doesn't approve of my sexuality. He had SEVEN children WITH 4 DIFFERENT WOMEN, and he would force me to take part in gatherings with a little half sister I have (16,F).
I have absolutely no trouble with my sister, but her mother is a devil with me. We had trouble in the past when I was younger, claiming that my dad was only hers, that I had no right recurring to him for help when I was in need, etc. She was not living with my dad when I arrived but I still chose to leave my dad a couple months later when I found a department for myself. I do not ever want to live with my father again even if it's temporary because it's destroying my mental health. Sadly, I'm looking for a new job right now and my father will sometimes offer to help, which I have to accept to pay some bills, which is also why I try to at least be in good terms with him.
Well, 2 weeks ago I was in my current job and I received a call from an unknown number. It was my half sister's mom. We'll call her N. I thought that my father had an emergency so I asked her what was up. She started yellingz saying that I have no right to ask my father for help, that he had a conflict with one of her coworkers, that my sister watched it all, etc. I did not know what to say at first, because none of it was my fault, and I never forced my own father to help me. I told her to go to hell and never call my number again. She then said "Ok, I will go to hell, because I will KILL you and your father". I told her I'm gonna call the police and she hung up.
After this disaster I called my father, told him everything, and he did NOT deny that he had a fight with her coworker, but he told me not to worry because he would talk to N. I continued with my day, when I got out, it was late, I told him I would not contact the police THIS time, but if anything else happens I'm getting N locked up.
Well now a couple minutes ago, I returned with my bf from dinner, everything was fine and I receive a call from my dad. He wants me to reserve the 2nd story of my building to give my sister a birthday party (because the building where I live is well known and a friend of mt dad used to live here) which means that my dad AND N are going to be here that day. I asked him if he did not remember what N did, which was threaten me, and he said "but what's the problem? This is for your sister. Not N." I told him sorry, but do not count with me.
I know now that my father is never gonna realize how toxic and horrible N is, that he will always put her above me and my sister, but I do feel bad about her. She is 16, she is in the middle of all of this, I wish she could have different and better parents, because when my mom was alive, she made sure I was out from any and every of my father's BS after he cheated on her. I also know that this may mean that my father will not help me anymore, but I honestly don't care anymore. I'd rather just take my time to find a new job and just be done with him for good. Now even more so that my boyfriend is present. I've been a people pleaser all my damn life and I feel this was THE time to put some boundaries.
Was I the asshole for denying this for my sister? If they do end up having her party here, what should I do?