One way I deal with FUD: see this as an opportunity to buy/buy again coins. With capital I had specifically placed on standby for such moments. Have to admit there is always some worry whenever I buy during times like this. Often, they'd go lower. However, I also ensure that I don't buy in one instance but over a few different price levels.
You are right about only using money that we can afford to lose. This is what I've been doing. The general principle is: even if I were to lose 100% of the capital in cryptos, I will only be disappointed and probably exasperated. BUT NOT face any sort of financial difficulty. Not even having to tighten my belt. At worst, I will not be going on a vacation.
I'd inform my wife how much I'm putting into these and not be secretive. Even though she doesn't know much about these cryptos (beyond bitcoin). That provides some check and balance in ensuring I don't risk too much (Actually she probably thinks I'm too cautious).
Although I believe cryptos are here to stay, I have to say that I'm no HODLer. More of a mixture of speculating, trading and some genuine investing. Based on my previous experience in the stock market, I make it a point to take some profits and money off the table when prices reach a certain point. But not sell all though. This ensures that I won't feel dismayed whenever the price falls (which happens quite often). I'd use the profits to buy again whenever it reaches a lower level. Like now.
Incidentally, this strategy has helped me handle the present fall much better. Thanks to previous big gains which I had taken profits on. Like with RISE and Navcoin especially. And Evergreencoin just yesterday. "Cash flow and capital management" - these are crucial in helping to handle FUD.