Harassment of NRI Husband and threatening to divorce

My sister is working as a software employee in an MNC, she got married in june of this year to an NRI from US. We promised them 20 tolas of gold and half of our house on my sister's name. They agreed and we met with the promise for gold. After three days of marriage he started to compare to his friends' who got married and started to prompt for more money from us. We initially thought there was nothing to worry but, he started to constantly harass her saying that she is not beautiful enough compared to the match that was fixed to him before our match and got cancelled due to some reason. From that day onwards he is constantly comparing for dowry that they promised (Rs.3 crores) and started to mentally harass my sister that the girl is beautiful than my sister and he had no interest in my sister and the only reason he married my sister was out of anger on the earlier match and to get married before that match. He constantly put that in light that he didn't like my sister and she is suffering mental agony. He left for US 3 weeks ago leaving my sister as she has to serve notice period here. He kept in touch and even from there he's abusing my sister that her skill set doesn't fetch any job there and asking her to get the house to be put on his name that we promised to my sister and to give Rs.30 lakhs as dowry. He took all the jewellery of my sister and put in locker and asked in-laws not to lend them. My sister asked some of jewellery to wear in office but, he’s bluntly asserting to choose between him and the jewellery in a harsh tone. He's talking to her as if to hurt her. Occasionally he's bringing-up that my sister has to suffer his abuses and should not share anything to anyone even if he beats her. My sister is shaken to her core and she's afraid of her condition after she leaves for US. She spoke to her inlaws and they are saying that they’d take care of it and nothing to worry. My father is a Low-BP Patient hence, we didn’t share it with him yet. I need your help in dealing with this scenario as we are unable to cope up with the circumstance. Do we have anything that we could do that my sister’s life is saved?!Please do help us.