Russian economic retaliation

Let’s say that the West slaps economic sanctions on Russia, and Putin responds by cutting off all oil & gas to Europe. How much would this hurt Europe, and how quickly?

You are making an interesting point.

European factories and consumers need those gas and oil supplies right away, or their stuff (cars, heating, factories, electric power stations, etc etc) stops working. The price would skyrocket because demand for oil & gas is fairly inelastic.

Russia would not be making as much money selling oil and gas : presumably they would sell a lower volume at a lower price. Less money would flow to them.

In dollars, I wonder who suffers more? I want to say Europe, but there must be a formal textbook answer to work this out.