Sextortion on instagram

Hello everyone,

I am a 19 year old male who stupidly sent out explicit photos to a girl who I thought was actually real and who I thought was really interested. They then later to threaten to send the photos to all my friends and family on instagram. They told me to pay them $500 to delete the photos, so I did. After this they requested another payment or else they will post it again. I freaked out, because I just graduated boot camp and do not have that kind of money to be paying him like that, because I didn’t know if they were ever going to stop. So I went online and went to a website called “digital investigators” who told me that they will help me. They seemed like good people and told me they had similar cases like this and that they were able to make the suspect back away and not post any of the photos. So I payed them to help me out. They told me to log out of instagram and that they will talk to him through there as well as through text. They told me to not go onto instagram as it may harm the investigation. They told me more I thought about it I realized that I probably got scammed again. I need help and I don’t know what to do.