Sorry with your loss.
I've recently heard that Tether has been banning/blacklisting Ethereum addresses that's related to scammers and hackers so that's the least that you can do for now. I don't know the procedure but you can contact them for this matter.
Email them @
https://tether.to/I Also sent them a message in this is their answer :
Thank you for the response
We are sorry you have fallen victim of a hack. Unfortunately we can not assist you on the matter. Upon checking the TXID of the transactions the transfer is neither sent from us nor to us Tether.to. Please contact the involved parties and ask for assistance.