I bought 3 btc on credit for 19k about. What should I do? I am way underwater.
You don't have any choice, you already lose a lot so maybe it is better to just hold until bitcoin will recover more and hit another ATH's this year. Having a patience can make you profitable in a long run.
if you do not want to wait then you can play altcoin to grow the bitcoin you have. if you buy bitcoin when it costs 19k and now the price of bitcoin collapsed then all you can do is wait, wait for the price to go back