Who's side do I take, my mothers?

Uhm, dont pick sides? It’s not really your place, and they shouldnt be involving you in this? You siding with him is definitely not going to help anything. I want you to think about this from her point of view (yes, yes, I know, she’s just wrong and you dont know why she does what she does), but indulge me for a minute. If you had a teenager whom you raised, and this kid is constantly trying to change you and make you realize you were wrong (and you didnt think you were wrong), how would you feel. Yes, I know, you’d be able to see better and you wouldnt treat your kids that way. But lets pretend for a moment. How pissed off would you be if your kid was constantly trying to change you?

Oh and you cannot change anyone. You cant. You can change yourself and how you react. But you cannot change her. Attempts will drive you crazy and lead to arguments and anger. I think it brings a lot of peace to accept that we dont have control over others. Only ourselves. Not that it is hopeless. Change yourself and you’ll change her. Start reacting differently. And also, she’s not being psychotic. She’s doing it for a reason. Try to figure out why.