How do I get my dad to divorce my mom?

I’m 15 and i really need my dad to divorce my mom. Sorry this is going to be pretty long and all over the place. To start i hate my mom, i’ve hated her for so many years and i know she hates me too. All she ever does is yell at me and my dad or even employees at the grocery store. I think she’s bipolar but i really don’t know a lot about it, but i do know that her mood switches on an instant one minute she will be fine and the next she thinks i’ve launched a personal attack on her. Today or technically yesterday because it’s 2 am right now, i was putting up christmas lights in my room with screws and even though i didn’t ask or want her help she just did it anyways, well one of the screws broke off and got stuck in the wall. I was trying to get it out but got frustrated and i told her i’m done with it for now and that il do it later. Then she just starts yelling at me, saying “ oh you just want your dad to do it, you need your dad to do everything i can’t do anything” even though i never said that. She thinks my dad has brainwashed me into hating her which isn’t the case, i’ve seen her yell and throw things on many occasions and came to the conclusion myself. On to the part i need advice on, my dad also hates my mom he talks about it all the time (sometimes it feels like he just using me to vent about her) he mentions divorcing her a lot but he never does. He gets my hopes up all the time saying he’s getting a lawyer and that he’s finally doing it (which he never does) and any time he does say it is when she gets mad at him. He won’t do much when she’s yelling at me which honestly hurts because most the time il just be crying while she has a meltdown. I don’t know how to explain to him that i NEED him to divorce her i need her out of my life, i have no motivation to do anything with her around me and im seriously behind on school because i just can’t do it. How do i get him to divorce her?