Thanks for posting the email addresses of the blackmailing team. That will definitely come in very handy as students look for reliable services through this forum.
May I ask why you believe that they developed a very good fake email to your school? The reason I ask is because these con artists actually use such devices to push their con forward. Do not take that seriously at this point. There is no reason to.
If the email is legit, then the professor involved will be notified and the paper in question will be assessed and investigated. A preliminary investigation will take place and if there is any evidence to suspect academic dishonesty on your part, you will receive an official communication from the school asking you to prepare to face the academic board of the school. Until you receive such a communication officially coming from the school officials, just relax. Take it easy. Continue to ignore the group.
They are just trying to ruffle your feathers to force you to pay up. Remember, they said they submitted the letter to your school. The long game has begun. They hope to ruin your holidays by making you worry. Do not give in to the mental and emotional blackmail. If that happens, they win.
They will now try to convince you that they can make the investigation go away once you pay the amount they want or negotiate an amount with them. That is proof that the email they wrote is fake. Send their emails to the spam folder.
If the university does make a formal communication with you in relation to academic honesty, come back here so we can help you sort out your defense.