Initially I haven't checked his address because I thought that he would make new address for each potential victim. Now I looked into it - now it's empty, but it received in total over 0.024 BTC in 2 transactions.
Where exactly I can report this address? I saw similar kind of websites, but now I don't remember their names.
The scammer probably doesn’t even know the risks involved in repeating wallet addresses, he's only interested in receiving bitcoin as ransom because he think he won’t get caught that way. I don’t think he truly has anything on you, people fall for this blackmail scam because of fear, $900 is only the first amount if a person falls victim and pays, the scammer will request for more money.
You can report the bitcoin address here
https://www.bitcoinabuse.com/reports/16hN8whHuZywJwMUGoiKRYC2p34SYQrWZ8