Bought a flat in husband name forcibly, husband transferred it

Dear sir, i bought a flat in mumbai in 2003 by takibg a loan and some by cash i was forced by my mil to put my husband's name too which i did then in 2006 due to maritial problems n hubby not working at all since our marriage in 1996 n fighting i left him n his sister paid the remainder of the loan up.my hubby passed away in 2011 n i was informed through friends on going to check my flat i got to know that b4 dying he transfered it to the sisters name without my knowledge n the society did not know i was his wife as i always worked abroad n only came to india for a month's leave b4 leaving him in 2006 he hid the house papers from me and said he did not know where the documents were.now my sister in law wants to come to a settlement as she recides in new zealand i do not wish to give her anything as i have all the bank stayements showing i paid for the loan from2003-2006 plus i supported my husband wirh everything including the household expenses n things in the flat. what should i do.