Husband and Wife seperation issue

My husband and In-laws have been mentally torturing me for last 2 years. Some times it was physical assault as well. One day unable to bear this I left my in-laws home and came to my parents home with my 4 year old son. My husband came to take me home but I do not want to go, because it had happened multiple times that he just remain calm for few days and starts to ill-treat me again. He is bearing the child's school fee and van fee ( 2500/- total ). He runs a small business and has a property which he and I hold it jointly. I thought that everything will be all right after some time if we stay away, but I came to know that he will take revenge on me if I go back home. I have not taken any legal action yet. My parents are old and cannot bear the legal expenses as we are not financially very strong and hence have not filed any legal case.. I want to know that is it possible that I can claim maintenance from him without divorce ? Can they claim my son's custody ? Please suggest what to do. Thanks in advance