Property dispute

I have bought a flat in 2004 worth 5 lakhs with 4.43 lakhs loan on my name with co-applicant as my mother n we paid rest balance 57k in cash, all emi is paid by me since 2004 august till date in November 2005. Iam afraid as my sister who is angry with me due to certain matters of family n due to jealousy will ask my parents to ask for claim in this house that they have invested in this house. Flat is registered under my name n mother's name. Society share certificate is under my name. Flat owner mentioned is my name on name plate below the building at the entrance. We had a room in chawl which we sold n bought this flat. That chawl was also on loan.. I took the responsibility of paying the loan so I think when we sold that chawl room, I also deserved some amount out of the sale n assuming that I have invested the profit of sale in this new flat I bought, Also iam the person who is paying emi on time since 11years n 3months, My parents have another property in native on which my sister has got loan n prepared house for my parents worth 15lakhs which my parents says my sister is doing n also 2k she gives every month for their expenses. Suggest me what should I do if they r angry at me as iam not their best choice to survive till last moment of their life. Should I be confident that they can't claim anything on my flat of 11years old and also I have the right to ask my share in the native property where my sister has created a house worth 15 lakhs on my mothers property. So that property has share for me also. Please reply,