How to fix a bi-polar mother?

Ok, before you assume I’m just some kid who’s in a fight with his mom and wants to vent, that’s not the case.

I’m 19, the youngest child in my family, all my other siblings have moved out. In my house it’s my mother, stepfather and myself.

So to my point, my mother craves attention and has all her life. She’s mid 50s and my stepfather is her third husband, after cheating on her last one with his best friend (who’s now the stepfather). She alienates absolutely everyone, has no friends because she’s driven them all away, and her mother was diagnosed with bi-polar. She refuses to get herself checked out and the last person who suggested it delicately (my cousin) was thrown out of this house and told never to show his face here again. She complains about no one more than her husband, and he’s the only one who she hasn’t driven away, but that’s because he doesn’t have a job nor a place to live if not here, plus he’s not doing so well medically.

If she doesn’t smarten up, i’m not paying to have her put in a home. I will legally disown her as a parent and let society deal with her. I’m asking for a solution, how to get her “fixed” so to say. As i’ve said, she drives away everyone before they even try to help her, and anyone who mentions her issues gets it even worse. I’m contemplating some chloroform and bringing her to the nearest mental ward.

P.S. I believe she knows she has issues, but refuses to deal with them. I say this because she keeps making little jokes about “it’s so weird that she’s nothing like her mother” who, as i already said, has been diagnosed with a problem.