What should i do to save my marriage?

I have been since last 3yrs... Me & my husband used to work in the same... in previous stage of my marriage it was very difficult for me to survive with my inlaws.. and forgot mention i live in joint family.. we both husband wife used to give our salary to my inlaws but whenever we had argument they always tonted me for not giving my whole salary on the other hand my husband gave and still gives his whole salary to them... now i have a child who is 15 month old.. i have seen in my family that they are least bothered about their daughter inlaws.. what always matter to them is there son and there grand children. Since the day my child was born they are looking for a way to take him away from me.. they keep on harassing me mentally.. every household chores are given to me.. every time they shout at me without my faults.. there are plenty of things which are not bareable... if i don't work they start making faults about me.. they always say to get back to my home if i cant live with them.. my husband is good but he never supports me whenever there is argument... my marriage is getting hell day By day... my inlaws are trying to remove me but want to keep there son and grandson.. i am afraid to loose both of them.. what should i do..? I love my husband and my child(boy) ... i asked my husband to get separated but he is not getting ready for it.. what am i suppose to do... they are making my life hell... they never allow my son to be with me... when he starts crying then only they give him to me.. they even keep on telling me to work indirectly... i cant even express what i am going through... my pregnancy period was made hell...n now worst... please help...