I would call child protection services on him. The relationship between your 17 year old sister and her father is destroyed forever. That is something you never forget and play over and over in your head. That is physical and psychological abuse.
call the police they'll sort him out
a father or mother should never hit there children no matter how angry they get.
You won't lose your father. He will always be your father but that household is not safe for you, your sister or your mom. He needs to get help so he can salvage what's left of the relationship with the family. He needs to be punished for abusing your sister. That way he will realize there are consequences for his actions. Report him now before he strikes again.
If he literally "punched" her like a man with his fist, then you should involve the authorities or at least tell a teacher, principle, school councelor or school nurse. Find someone in authority that you trust and they will help you and your sister. Your sister really needs you to help her right now. Find someone you trust and tell them. They will help you.
In that case, find someone you both trust and go to that person together, so you can give eachother the support you both need.
My dad tends to lose his temper a lot too...Even if your sister was out of line, she is only 17 and can't be truly expected to always act like an adult. I suggest that you talk with your family about group family therapy sessions. I wouldn't contact authorities just yet, perhaps talk about the situation with a close friend or trusted adult and decide what the best way to handle the situation...I promise your sister will remember what your dad did and how it made her feel for the rest of her life.
I just know because I've been through the same experience, I didn't want to lose my dad because my family needs him, so calling authorities is never easy. But you have to assess if your sister is in real danger, or if you can figure out a way to prevent the situation from happening again. Talk about what led to the violence and how it can be prevented.
Depends ik this is late but have in consideration the actions of both sides , how hard was the punch? does he do it often as in every bloody time she does something disrespectful to him. what did she do? back in the days youd get a swollen cheek and a tomatoe butt if you ever disrespected ur father, just saying... ( people overreact, admit it some kids/teens need a slap/punch in the face some of the times ;)
You have to tell someone, this will keep on happening if you don't. I can understand your feelings about the telling, but it is for you and your sisters safety.
I am so sorry that you are going through such tramatic experiences. These situations are very hard to deal with because where will you go and who is going to take care of you. The authorities are going to help by putting you in a foster home, which might be worst for you and your sister. As I think I am am wondering if you have a family member that can help with their understanding. Keep you or talk to your Dad about his behavior. You are almost eighteen and can move out and take your sister with you as a guardian for her protection. There might be help with the social services to be caring for your sister and provide you with housing if necessary for the both of you. God Be With You. Peace.
You have a greater loyalty to your sister than you do to your Father, she really needs you, be there for her, now and forever
get help fast.its hard. i had a friend who was sexually abused by her dad and when she finally had the guts to report him her mum and the rest of the family wouldn't talk to her because he was the breadwinner. he went to jail and she to an orphanage.
Call the police department.
Potentially involve the authorities.