How fucked am I?

Foliar feed them. Its the single way to get nutrients directly into the leaves but watch those buds. Half strength nutrients and what foods and supplements do you have? you could do with adding a surfactant which breaks the tension of the water and enables the plants to take them up even better,its in some additives. Cover the buds the best you can and spray the leaves 1 at a time if poss.

Well the ones that fall off easily are too far gone. the green ones are well-attached. Some portion of your leaves died. Once you start watering again, that stops,but the damage that was done cannot be undone in some cases.