A good recipe to not be "frozen in fear" - as you will know - is to just gamble with a small percentage of your BTC funds. I am using about 25% to trade and catch lows to buy more.

During the flash crash I had limit orders on Bitfinex for 412 and 534 (not pessimistic enough). They got filled and I watched without trying to mess around. Still my stomach cramped seeing it going down to 100 but I was perfectly sure that BTC was not broken totally, that my main BTC funds were in cold storage and that I just baught significantly lower than I had sold before.

So, point here is that one has to first rick oneself and chain oneself in a way so that monkey-mind has little chance to take over once the action really begins.
A lesson that I learned from previous losses, which were apparently necessary to punch this lesson into the deepest depth of my body consciousness:-)