Are you sure he didn't have your password? Has the email account you registered your steam account with ever been compromised and was the leaked password the same you still use? https://haveibeenpwned.com/
One of the IPS of those scammers is https://ipinfo.io/AS9299/49.145.224.0/19-49.145.225.0/25 He's a scammer from the Philippines. Blue-Valve Employee#6161