Mental harassment by husband parents after marriage

My parents-in-law have two sons. i got married to younger son 2 year back. i gave birthday to baby girl , but sadly she has birth defect called microtia. Although my husband earns, but the world came cracking down on us when our child had the birth defect. my parents in-laws were never helping us financially and we were living on our own in bangalore city which is costly. So, we tried to ask my husband parents to help us in treating our child, as we were not able to by ourselves. My husband used to give money to his parents since he joined his job(which is almost 6 years). Now due to this issue, we have to ask from them. but in place of helping us, they are asking us for money. Whenever we argue with them that why they are not helping us, they threaten my husband to be on track with them but then say are joking. They even said that they will remarry my husband , but then covered it by saying that they are joking. There are mutliple instances , after my marriage, where they have made bad remarks, abuses but i used to ignore, as we never thought that we would be facing such issue with our child in future. My father has given jewellery , furnitures, appliances etc in marriage along with some cash all in good faith. But my parents- in -law are in demand of more money from me and my husband, in place of helping us with our child(7 months now) who is not able to hear. Even though they keep on abusing me, insulting me and my husband, we ask them for help. But we always get bad remarks from them. But they have no issue in help their elder son , wife and his two children. They are paying their schools fees, rations, milk etc. But always make excuses in our case where we need help with our childs treatment not anything else.