my biological 'daddy' just found out about my existence what shall i do?

my mother married my father at the age of sixteen she was in love a few years later he became abusive and violent towards her at the age of 20 she got pregnant and together my grandmother, auntie and mother decided that adoption was the safest route for little bump (me) so my mother made up an excuse about a sick aunt she had to look after bout four months into the pregnancy he refused to come as she knew he would my mother met my adoptive parents and i was adopted at the time of birth a month later my mother returned to my abusive father it was a closed but not closed adoption and i still saw my auntie and grandmother although i didn't call them that about two years ago i was told i was adopted and this story of why i still call my adoptive parents mum and dad but today when my auntie visited she told me my father had found out about my existence and had hospitalized my mum i really don't know what to do im 15 years my adoptive parents are thinking about totally closing the adoption and moving to Australia to be with my adoptive Mums family and my auntie and grandmother although rather upset are in favor of this and have offered to pay any expenses i don't want to lose contact with my grandmother and auntie and i want to see my real mother but my father is the one thing stopping me my mother refuses to testify against him and he has been taken to court three times on account of violence and abuse but been cleared of all charges because my mother denies it and they can find no proof she and he always have sound alibis please help me what can i do i really don't want to go to Australia sorry its so long I'm just so scared