I bought 3 btc on credit for 19k about. What should I do? I am way underwater.
Absolutely you are losing mate, it's price today continuously at half since you buy it. There is only 2 options for you, sell it and buy other coins or keep on holding until price will be back again..
Why buy other coins and risk even more?
Selling will only hurt you too big, I want to ask you, are you sure about the future of bitcoin? if you're sure the only option is to holding you bitcoin, holding it will keep you away from losing, I myself also believe the price will definitely return to that position even much higher, You just need to be patient, yeah adding coins / assets means increasing risk