I was forced out

I'm 12 and bi my mum didn't know but I came out to my school online and everything was fine. Then I found out a few peeps went around the school telling people. So I told a teacher. That situation was sorted out but then she told me she had to ring my mum to tell her about what happened. That meant my mum would know she said she didn't want to force me out but she had to. She did know my mum knows she said she would be supportive but she doesn't think bisexual is a sexuality. And she calls me a lesbian. She uses the wrong sexuality to insult me. She will call me a lesbian cunt and shit like that we don't get on that well wat should I do. I hate the fact she uses it to insult me. I'm sorry if none of this made sense but I needed to rant to someone. Plz some help on how to deal with this. I'm already very self conscious person this makes me feel worse