Fake documents like gpa ...

Hello Sir's / Madam's , I Started Construction for my land last year September 2015, With a builder. Mistake that i did not sign any agreement. He has taken 10 months and still only 50 % of work is completed and he has taken 80 % of money . he stopped work after getting last payment.. Now he is saying he is done with all the money and needs more money to complete the project. I said i wil do it on my own , i have already encountered Loss , now he is creating Problems , saying that i will land in more Problem.. Then few other Owners Contacted me and said he did same thing to them.. and to all of them he has prepared Fake documents "Saying Owner has to pay amount to Builder" and he threatens with those papers and grabs more money. Now my worry is How do i encounter him and also the Documents which he prepares can be produced in court. I have his Emails ,, Messages ,, Money through Bank fund transfer , His bills etc. Please help me with this. As this is my fathers 45 yrs of Hard earned money , he is 60 now ,, my 7 years hard earnings , plus bank loan etc.. Please