If you're currently the defacto CEO, this is going to be a lonely thing to do, but you might need to be the one to set the example of optimism in your work. That doesn't mean you need to appear upbeat and happy, but your friends/coworkers could use your help here. Even if you don't feel optimistic internally, rather than giving up, perhaps after making sure investors and customers know what's going on and a short break, you should set the example of moving forward (I intentionally don't say "moving on", which is thankfully not a prerequisite for moving forward). This doesn't have to be the end of this company. I don't know what moving forward looks like for you right now, and you probably don't either, but the best thing for your employees is to see you optimistically giving it a go (again, you don't have to be happily doing it, that's not really what I mean by optimistic)
My condolences, I wish you the best in this difficult time.