If it physically HURTS to eat, perhaps going to the doctor would be a good idea? At the very least, your parents can't allow you to not get medical help, especially if you "play it up" and complain of severe pain. If you get to talk to the doctor privately, ask them for their advice? You shouldn't have to deal with an eating disorder or any serious mental health issue by yourself without support.

I'm sorry your family is abusive like that and not supportive.