Divorce or separation form my previous nikah.

Hi, I am a Muslim women married to a Hindu Brahmin. In 2005 he verbally converted to islam and by arranging Maulvi he did Nikah with me in presence of two non muslims and one muslim as witness of Nikah. we started living together in his own house and were blessed with a son,But all of a sudden it came to my knowledge that he was already in a arranged marriage but the wife for his ill treatment to her used to stay in her Parents house.When his this cheating opened to me I was completely broken but had no means to go any where since my Parents were angry on me.Gradually he started insulting Islam and said it was a false nikah I performed, He started beating me,was not providing me even my basic needs,no financial help even.I filed a case against him under D V Act,but due to his good financial status he is hiring good advocates and till date no appropriate proceedings have been initiated. I stay in a rented house with my son and whenever he wants he threatens me to take back my case. Now it is almost 7 years of my separately living with him. Will my this state will be requiring a divorce or it is a understood divorce since years passed he is not bothered for me and my sons needs. I am again wanting to get marry to start a new life,the man proposed to me recently is again a Hindu Brahmin,So what will be a legal way for me to marry again.