first of all if you want to convert bitcoin to anything it must always be to fiat and not a centralized altcoin. specially not something as shady and risky as tether!

secondly whenever you see a big drop and want to think about selling you must do it in early minutes or hours of the drop and not 3 days after the drop started and price went down already. right now you have no way of knowing whether there is any more drops or not because there is no reason for it and there has already been a 30% drop which you missed. selling now is taking a huge risk.