Big Mistake, transaction from BTC to Tether (USDT), please help.

Hello everyone.

Let told you my big mistake:
I transferred funds from my Wirex BTC account to my Tether Bittrex account, yes, big mistake, my questions:

Can I get back my funds? If yes, how?

Wirex told me that the transaction has been completed, and Bittrex told me that the just can try to get back my money is the transaction I over 5000$.

In blockchain the transaction status is (Gastado).

What can I do?

Many Thanks and have a nice week,

stay calm and wait for your results, every action will cause a reaction