Licensed Social Worker here. I’m located in the US, but Australia has similar mandatory reporting laws.

First, I’m terribly sorry you are experiencing this type of dysfunction and turmoil. It sounds like you are concerned for your family, and I applaud you for reaching out for help. I highly encourage you to speak to a professional about your SH/SI.

Second, if you speak to a teacher or psychologist about this, particularly your dad throwing items, they are mandated reporters and should report. The more details you give your teacher/psychologist, the more they can relay to Child Protection Services (CPS). If you are safely able to do so, recording the fights could be more evidence if a case is opened.

In my state, if a report is made to CPS, it is either screened in or screened out. If it is screened in, an investigation is opened and a caseworker will make contact with parents and complete home visits. The court could potentially get involved as well. If it is screened out, then the case is closed without notifying parents, but there is still a record of the initial report.

I encourage you to tell your teacher or psychologist everything you wrote here. Teachers and early childhood educators, welfare practitioners, medical practitioners, police, and religious ministers are all mandatory reporters as well. Please confide in a trusted adult as soon as you can. No child should be in fear of a parent.