I don't care what someone's place is in my life, I will not defend your actions. Brother, husband/boyfriend, family member, friend, even my children. You do not EVER hurt someone emotionally. Absolutely NO physical abuse, NO MATTER THE REASON. It is NOT okay under ANY circumstances. I am guilty of physically fighting with my BD. Yes, I've hit and hit back, but regardless I shouldn't have unless it were self defense.
If you're being hurt, DO NOT STAY. If they are breaking you down brick by brick, DO NOT STAY. I don't care how long you've been together. If it makes you feel like you're scare to turn around, like you can't do anything right, like you're being neglected, like you are alone, GET OUT. The only way it gets better is when you leave. They can get help if they choose to, but do not stay through that process because chances are they can slip up and take it out on you. It'll be scary to leave, but do it for you. You don't deserve to be treated like that. You deserve to be happy & content with your life.