Sorry to be the barer of bad news... But if you entered your private key on a phising website, and they used your key to spend your ETH and fund their own addresses, you've lost your ETH as soon as those transactions were confirmed.
No way of getting it back...

Best you can do is keep tracking the thief's addressess, crosslink them against any social media you can find (see if he posts one of those addresses) and hopefully one day law enforcement might find him (potentially by accident), and you can start a lawsuit against this person to get your funds back.
A different route is to try to contact his domain registrar and hosting provider... Maybe they have his name on file...