Hi Ben,
It's good you feel you can reach out for support from the people in this forum.
The following link has some very good advice about domestic violence:
http://au.reachout.com/find/articles/domestic-violence
Some hotlines you can ring to get advice and support are:
Mensline 1300 78 99 78
Relationships Australia - 1300 364 277
The family GP could also be an invaluable resource and support. Your GP can link you in with supports for you and your children while also linking your wife into mental health support.
Hopefully these resources get you the support you need. No one should have to live with violence in the home.