<human>: Can you give me the gist of the text in a nutshell?

My dad is emotionally abusive and increasingly irate as my sister develops into her rebellious teenage self. He sometimes causes her to have mental breakdowns and that just makes my dad even angrier. When he is screaming he is literally inconsolable and it's happening more and more often. He cannot understand that he is being abusive and violently refuses any suggestion that he might need help. The more he restricts, the more she resists and everyone knows where this goes. 

 I am not at home often (college) and cannot fully see how he is treating my mom. She doesn't want to get him help because of how he might react physically. He has threatened everything under the sun once when I suggested a counselor. He believes nothing is wrong with the way he is acting and will never forgive anyone if they go through with contacting help. Knowing  this, can I do anything to help my family? Please. I'm in the US if it matters.
<bot>: dad becoming super angry at rebellious teen daughter and developing signs of mental illness, I can't help my family as far as I can see.