Divorce for harrassment

Hi, I am Mrs.Induja from Tamilnadu. I want divorce from my husband who harrasses me for minor issues. I don't want to live with him. But, I have a boy kid who is going to complete 4 yrs by this october. I am going to take over a job to retain my child after divorce to financially support him in aspects of his health,education, etc. But as a Fresher, my salary would be probably basic and lesser than my husband. In that case, will the court agree to leave the child to my custody since he is under 5 years old? Right now he is under his grand parents custody since he was afraid of the situation when my husband harrassed me pulling my hair and my I left the house. I asked my kid if he comes with me. But since he thought that I am angry on him out of his innosence and doesn;'t realise that it was his father who harrassed me and that's why I am leaving the house, he refused to come with me.But can I fight in court saying the factors that his paternal grand mothers are old and that if my husband happends to remarry, my kid will have to face mental harrassment by step mother, so I want my child with me.I don't have my mother and have only father. He is ready to support us with his earnings too who is still under private company job. Harrassment being the genuine reason to get divorce, will the court punish my husband and will the court order to give maintanance cost (jeevanahamsam). Or will the court ask for evidance that I was harrassed? Also, my kid doen't ask for me since he has become comfortable with his parents. So, will the court ask for his preferance also as under whose custody he wants to be? Please guide me with this. I want my child back. I cant really imagine living without him.