How do I tell him?

I’m bisexual, 18 F. I have a very loving supportive side on my mom’s family, who believe that love is love and that god would never judge you for loving the same gender. I have a transgender older brother, and they are supportive of him too. My father and my mother are split. My dad’s side is very religious, my great aunt being a nun, and my great uncle being a priest for the Vatican. He would travel, giving speeches about gods word and overall that half is very religious. My dad was on the phone with me one night and I talked about a friends wedding I’m supposed to go to in June, she’s marrying a man. I was talking when I accidentally referred to her fiancé as a “partner” that seemed to set him off as he went on a rant about how “gay people are wrong and it’s weird and bad” now here comes the kicker. Me and my dad never had a good relationship, he’s an alcoholic and we never had a good bond growing up. He proceeds to go off about my brother being born a female, and that “if my daughter was ever an (insert the F slur here) , I would disown her”. I love my dad, and he always told me that he would support me no matter what I do, but that ripped it all away from me. I wanted to tell him right then and there that I was gay, and that if that meant his love for me was conditional, that he wouldn’t be my dad at all. He’s supposed to come see me in June for my graduation ceremony. There’s this girl I’ve been talking to and I hope to ask her out soon. Any thoughts? I don’t think I’ll ever have the guts to tell him that his only daughter doesn’t meet the expectations that he wants.