My homophobic mother

hello.. recently ive been feeling very hopeless. I just need some advice on how to deal with some stuff to be honest. Ive been doing terrible at school. I spend all my time studying yet I cant get a quiz or test grade above 65. I sacrificed my entire social life. I only talk to my girlfriend and my tutor. But no matter how much I study I still fail. I don’t know why. I know all of the material. It might be because I have a slight test taking anxiety. After failing so much I guess I got scared of taking tests. But even when I think Ill do well and know everything, I manage to get 60s.

Another thing to add, my mother found out i was bisexual. (im only 15 years old) This was a while ago, and she told me she didnt understand and she would try to. Recently, she came to the conclusion that she dislikes me. She brung it up out of nowhere the other day, telling me that im a disappointment and that my girlfriend was ugly. Calling lesbians girls with low self esteem because they cant get a boyfriend, which is why they go to girls. She said that she didnt want my younger brothers or daughters to be like me and not to influence them. She told me that I wasnt normal and if I were than how come its illegal to be gay in other countries. She told me it was not natural. She told me that I would never get to experiece what a penis feels like. She told me that lgbt teens are depressed and suicidal BECAUSE they are gay. Not because of their homophobic parents *cough*. She told me that I should move out, and she was going to kick me out. She told me that I should live with my girlfriend since she cares about me so much. She told me that my girlfriend should pay my class dues and buy me a winter jacket (because she doesn’t want to anymore die to me being bisexual). She called me selfish, too young, and told me that Im not allowed to date until im 17/18, and if so it can only be guys. She told me she would never accept me unless I was 25 and telling her that I was bi, because thats when the brain is “fully developed”. She said that shes not homophobic and told me that my generation is fucked up. She said that i was a whore, that I wanted to be with a guy and a girl at the same time.

She blamed me for lying about my relationship, but I did it because I wanted what was best for us as mother and daughter. I knew she was going to act this way. Why would I want my own mother who hates gay people to know I have a girlfriend? I wanted to reserve our good relationship. But now its all gone to shit. When i try to explain things to her she calls me disrespectful. She says im not deserving of respect because im the kid and shes the adult.

When I had tried to explain to her that gay kids were often depressed was because of homophobia, she told me

“if you wanna kill yourself, then kill yourself” in an angry voice. When I cried and told my father she played it off as a joke. But should a mother really even be joking about that. Those wourds should not even be a thought in a mothers mind. I guess im in the wrong here though, because im only a child.