Property issues

We are total 5 members in our family.Father ,Mother,sister ,myself(son),wife.Before my marriage , father asked me to take a loan (mortgage)of 12 lakhs in my name by using an office which he had purchased in my name .It was for house renovation and father said he will pay it.But after marriage he said I should only pay as it's in my name or there will be loan issues from bank.So I started paying.He used to trouble me and my wife a lot and harrased us a lot and kept lot of restrictions in his home and kept saying leave the home...Finally he asked us to leave the home.Then in August 2016 I left and have been staying in a rented home since then.Suddenly in March 2019 he called me and said he will buy a flat for me on loan but in the name of director as I am a director in his company since he wants tax exemption.After approaching bank, branch manager said loan cannot be taken in the name of director.It should be in my name itself.So he agreed with the bank manager.After 2 days he called me saying I have to sign a document saying I will not get any share in his and his ancestral property because this flat will be in my name but previously he already made me take a loan and I am paying it.What guarantee is there that he will not repeat the same after taking the loan on flat.What are the legal implications of this. List of father's property 1 building (3 floors) in Kerala- ancestral property (obtained from his mother). 1 office in Goa (self purchased property) 1 home in Karnataka(self purchased) 40 cents land in kerala(self purchased). He asked me to sign a document saying I will not get share in any of these if he buys a flat in my name. 1)Can I know what rights I have over the above said properties. 2) if I go back to his home to stay there permanently with wife and if he refuses, what are the legal implications ? Because I have financial issues. 3) if he writes a will what rights I have to claim some share.