Changing baby’s surname

My ex and i aren’t married but i let him put his name inside the baby’s birth cert and his his surname. we have broken up and i wish to change to my surname. However, i don’t wish to contact him because he wants to be in the child’s life to get back with me. He have also threaten that his friend will beat me up for leaving him and he will beat my future boyfriend up. He also refused to let me go back to stay with my family when we were together. He also raped me to get me pregnant. Despite all these, ICA says he need to agree to the surname and dilect change (the child’s primary race is chinese but his dilect is tamil. ICA didn’t even ask so i thought they will use common sense answer follow primary race). I don’t want to contact him because of the trauma and anxiety. I also can’t stand seeing his surname and it makes me cry. What should i do?