Separation !!

My husband is an international full time student here in US & I’m here being his dependent. We originally belong to India. We’ve lost our oldest child to leukemia 4 years ago and now have 2 kids . Since the very start of marriage, I’ve caught him cheating/flirting,watching porns & what not. After every episode, he apologized and promised but ..Now that we’re here in USA, I’m completely dependent on him for everything. I’ve even caught him cheating one year after death of our daughter when I was pregnant with my second child & when my son was born . So I’ve no trust in him at all. He’s very rude to me for last few months & threatens me to send me back to India if I don’t follow his lead in everything.He’s emotionally abusing me .He threatens me that he’ll divorce me. I’m not a US citizen so I don’t know if I’ve any rights to live here independently at a separate place. I’m not eligible to work here so I can’t just go & start living somewhere. I need to know what will you do in my situation and if there are any organizations who can provide residence for my kids and myself. I can’t go back because my oldest daughter’s grave is here and it’s a matter of spiritual peace for me to visit her and talk to her.Please advise me what should I do.