Sister's share in fathers property

Dear lawyers, I would be very thankful if you could guide me as I am in the situation I describe below: I am 62 year old and have one sister and no brothers. I have always lived in the house my father bought and built. My father passed away in 2005 (and mother in 2000), however, I continued to live in the same house after his death. During the time my father was alive, and after his death, I invested a significant amount of money in the house as the house was in a bad shape structurally. Sections of the house had to be reconstructed. Of course, my sister has never lived in this house since she got married in 1973. The property is currently in my name. My sister, after my fathers death had given me an affidavit bequeathing her right in the property which helped me get the property transferred in my name. Now, as I am thinking about selling this property, my sister wants a share. Please advise, what share in this property my sister could reasonably claim and get? How does the fact that I have occupied and maintained this property all my life play into the division of shares between me and my sister? Thanks in advance for your advice. Regards.