how do i get my mom to see what shes doing to me?

my mom has this fiance who is an asshole who disrespects my family and i all the time even my dad and he doesnt even know my dad. he told me i was a demon and a person of satan because i told him if he was going to keep verbally abusing my mom he would need to leave my house. he doesnt even live here he has his own apartment but he doesnt even go there anymore. i feel physically and mentally ill all the time now because o the stress he puts on my family. i finally snapped today after he said a horrible thing to me that i will never repeat and i punched him in the face and i couldnt stop punching him my mom and brother couldnt even hold me back and all day my mom has been defending her boyfriend and my bro and i have been fighting with him all day and he made my 16 year old brother cry because hes just treating everybody horribly and hes affecting my diabetes really badly because of the toll hes taking on me and i might have to go to the hospital. im really depressed and i have anxiety all the time and i never eat always feel like im going to be sick and he continues to abuse my family, he even physically abuses my animals and my mom does nothing about it, she claims its because hes really sick with his bipolar disorder but i think thats bullshit ive known him for two years doing this **** and he just got diagnosed with it two weeks ago but hes always been like this. im on the verge of running away i want to die. he is ruining my life. and after i punched him he called the cops on me i am a 14 year old girl what kind of loser gets scared of a 14 year old girl seriously if he doesnt leave god knows what i will do to him next please help me get my mother to understand what the hell he is doing to me and my family.