Sister-in-law and my brother are harassing me mentally, also troubling me for money.

My brother is a mental patient. His wife and family had lived at their place for 4 years and I treated him and finally after spending 1 year in Mental Hospital he got well ( although he will remain ok only if he takes medication. ) After a few months after discharge from hospital her wife filed for divorce. They agreed to return on some conditions. One of those conditions was that I will also contribute money for household expenses. I don't remember whether there was any ratio fixed or not because I like a stupid guy forgot to obtain a copy of the agreement. Now they are harassing me a lot. Out of 20k which I earn almost 13k is gone on grocery, property tax, and other expenses in a few days! When I had requested them to pay electricity bill just for this one month, they started threatening me that they would take legal action against me and forced me to give Rs3500 to them leaving me with just Rs1500 for the entire month. I am really fed up with their behaviour. Is there anything I can do apart from taking my life. Please help me.