Father remarried, drinks heavily, and it's taking a toll on us - need advice

Assalamu Alaikum - I’m a daughter and my father, 52, has remarried. He basically remarried to have someone to drink with, since my mother doesn’t drink. Now he spends about four days at the other house and three days with us, and when he returns he expects warm welcomes and affection like nothing changed. That really hurts. His new wife has many children (around five sons). None of my siblings agreed with the marriage, and my mother was also against it. He has been drinking heavily for over 15 years - not just beer, but strong liquors every night (vodka, whiskey, tequila). When I was eight I found out and I kept praying “اللهم اهديه الى الطريق الصحيح,” but he’s only gotten worse. He used to hit my mother when drunk; that has stopped for now, but the drinking and coldness remain. Most of our relatives sided with him, so it feels like we’re alone. We’re financially stable and he’s well-off. My siblings and I have good degrees, while the other family doesn’t; I’m not saying we’re better, just that it makes me wonder why he chose them over us. He constantly brags about his second wife and spends less on us now. I believe she’s using him for his money. When we bring it up, he says “Islam allowed me to do this so you have no say, I’ve done nothing wrong.” He told me when he was remarrying: “I gave you the best life and made sure you lived luxuriously, so I have the right to live my life now.” I didn’t respond because I feared my words would be seen as disrespect or عقوق الوالدين, so I quietly left the room. I understand why Islam permits polygamy in certain circumstances, and I don’t blame Islam itself. I blame my father for using religion to justify hurting us and for remarrying just to drink with someone. That’s not what Islam teaches. There are also worrying things about the second wife - people say she does سحر. Yesterday I found a dead bird in our yard with its insides out, and our roof has many ants; relatives say these are signs of black magic. I don’t know what to believe, but it adds to my fear and stress. This situation has affected me deeply. I’ve been diagnosed with bipolar II and moderate depression and have been in therapy and treatment for two years. Still, whenever he sees me he acts like he’s done nothing wrong and tells me I’m his favorite daughter, which is confusing and painful. If he supposedly loves me, how can he hurt me so easily? I don’t understand him. I have many exams coming up and I’m struggling to focus. I need practical advice on how to cope with him, protect my mental health, and handle the family dynamics. Any dua, coping tips, or ways to set boundaries respectfully within Islamic guidelines would really help. JazakAllahu khayran.