Failure to submit project handover

I was joined as trainee for 3 months with 10k INR compansation. They told after 3 months I will provide you full time employee with 20k INR compansation. But they are didn't given offer letter to me. I was worked 2 months after that trainee. They are given stipend 10k for that 2 months. I didn't get salary properly on date. They told I will given salary on or before 5 of every month. But I was getting salary on above 5 only. So I was suffered financial management. Salary delaying of regarding April month they promised to get pending amount in subsequent 3 months cycle. In may month of salary I get only 10k. I asked again to employer. He told again pending amount I will given to you above 10th. I got suffered very lot on that day. Hense I called to employer then I said I will relieve from the company. He told like you need to finish ur project handover requirements in 3 weeks. I didn't go that company after I informed employer. Now he was blackmail like "Failure to provide a satisfactory response within the specified timeframe may leave us with no choice but to initiate further actions, including but not limited to: 1. Blacklisting the candidate due to poor work ethics. 2. Communicating the work ethics concern to respective future employers. 3. Reporting about professional conduct with agencies like Nasscom, NSR, EBC's etc. 4. Pursuing legal recourse to recover any damages incurred due to failure in delivering your handover duties." What I will do. I need to join next company. I can't able to that project handover requirements. Because I was already suffering by company from past two months. Given me solution.