AUSTRALIANS your help is NEEDED?

My friend is on a single parent pension and has young children the youngest being 9 months old, recently her family member is threatening to dob her in because her ex is sometimes there, he never gives her any money and he aggresive so she is to scared to tell him to leave, she has no criminal history . Will she go to jail . im scared she will because it will kill her to loose her baby so young, she has no family members there to look after her children either, she is petrified so much. Please help will she go to jail. she been on single parent pension for 8 years, he comes and goes and if she wasnt on it she would be homeless