That must have been a neem or other oil product.
Soapy hot oil water? Noo!!1!! No added heat, and you already have an oil problem.
The dead leaves won't recover but with luck you may grow new ones if the plant is not totally dead.
Pyrethrin-based insecticides don't do that.
Next time around, apply your neem oil only VERY lightly. A few light applications will build up a protective film on the leaf surface.