Mom is getting divorced....again

My mother has been divorced many times. Which I️ am not here to explain why and that I’m upset with her over that. Her new boyfriend emotionally abuses me, to the point I️ do not eat to avoid him. I️ eat once a day at school & no anytime other than that. He calls me “child” “worthless” & tells me that I️ do not matter. My mom tells me that he will change, but I️ am scared he will begin to get physically abusive. He tells my mom that none of her kids care about her & that we’re all lazy and do nothing. He is in the military so he expects everything to be clean, but I️ was not raised that way. My mom didn’t have time to worry about that. He has no kids, too. My mother keeps trying to change me & my brother and how our lives are, but I’ve already had plenty of change. I’m 15, my brother is 18. He has caused me to become depressed, but not suicidal. I️ feel as if my mother does not care for me, because she does nothing about his behavior. You can start to see my ribs by how skinny I’ve gotten:

All other family lives far away so I️ do not have any options. She will not listen to me, so I️ need advice on how to get through the next few years. He is always angry with me & yells at me constantly. Which gives me anxiety attacks from my mom & all her previous relationships, that have caused me PTSD. I️ stay away to make her happy & avoid conflict, but sometimes I️ have to talk to my mom & cant always avoid him. I️ keep having nightmares about him hurting me. I️ don’t know what to do... I️ came home from vacation Saturday, today is Monday, I️ did not have school today. That is what I️ look like after two days of not eating. I️ am miserable. Someone please help... I️ am at my wits ends...