I made the mistake of buying an essay online, due to having surgery and no time to write it. Now the website is trying to get more money from me threatening to call the university and the Board to show the paper and my name and the conversation we had because they claim I have to pay for copyright, not just the price for writing the essay. They say they did not know about this, as I asked why did they not tell me about this additional cost before, so I should know the essay is just for me to read, and not submit it to the University, as I stated clearly what I am going to be using it for. Please, could you help me clarify this? Thank you.
As Putvi says, you are being extorted and this is a criminal matter and thus a matter for the authorities in your jurisdiction.
However, you have a second problem entirely apart from that - you almost certainly broke academic ethical rules by submitting a piece of work that you did not write as your own (these things are pretty cut and dried in academic circles). This will not go away. Regardless of whether your extortionists are brought to justice, they can still release your details at any point in time and ruin your career, or it can come out in other ways.
Own up to this with your university as soon as possible, and see if you can make it right. This will be hanging over you for the rest of your life, and can drop at any moment - these sorts of things have ruined people before.