File a divorce suit from Australia - Wife living in India

Hi, I am married for 18 months with a 7 months old kid and have been living in Chennai. I am now in Australia for a company assignment till December this year. Ever since my kid was born my wife started showing her hatredness towards my parents and started fighting at least once every week and leaves my home and stays in her home with her parents while the kid stays with me and my mom. She always stays in a confused state of mind and started assuming that I will leave her and get married to someone because she is not perfect in anything such as she is not intelligent as much as I am , she is a misfit to me etc., I used to comfort her but over a period of time it became too much on my head and slowly became a mental torture. Then she suspected that I had secret sexual relationship with my mom too.. It was the time everything became serious in my family. Both side parents and relatives did some talkings and asked her to apologize to my mom and me which she did. Later she started accusing that my parents were trying to separate her from the kid. She always left the kid and went her home and then comes after a week but accused us. Off late, she was telling that she feels that everybody around her indirectly harasses her and she feels like killing me and the kid and run away. Since, the torture kept increasing I reached out to Women's police station and lodged a complaint then they advised family counselling and the family Councillor reported that she has self doubts and some guilt is making her behave so and also suggested to contact a psychiatrist which I did not one but with two psychiatrists. Both of them reported that she has grew up with negative thoughts, self doubts etc, and she has to come out of it herself and prescribed medicines. She was okay for 2 days and 3rd day started accusing that we are trying to kill her by giving her these medicines. I not can't take this anymore. Her family says that this is some ghost attack on her and some sort of exorcism is required. And she is also making false accusations that my family is abusing her physically too. I have decided to go for a divorce. But, I can't give my kid to her she can't give him a better life. I would like to know if I can send her a divorce notice immediately and then go to India by December to fight the case. Also, what will happen to my kid? should I have to leave him to her ? Is there a way to keep my kid with me. I am very confident that there is no other way to deal with this anymore. Please suggest.