ANSWER:
Blackmail is an endless road. Once you start in it, it will never stop! Therefore, DO NOT respond to any of their threats and make duaa to Allah to conceal your sins.
If you respond to their threat, they will keep on blackmailing you until you do all what they want you to do.
I know of sisters who responded to blackmail fearing that she would be exposed to her father. They took all of her money, forced her to steal her mother’s jewelry and after that forced her to come to their home, pose in nude phots and then had sexual intercourse with her repeatedly and filming it with their friends. She became a prostitute and disgraced her parents and family because of her fear of being blackmailed.
Do not respond to any small demand. Block them and ignore them and let them do whatever they want to do! This is Allah’s will and you need to pay for your previous sins no matter what the consequences are. Simply trust Allah and make duaa