Fossil gas was a minor energy source for germany and the eu. It was costly to replace 2 years ago but at this point the cost has been paid and the energy is sourced from other fuels.
The german car industry was bound to fall ever since they refused to research electric cars decades ago. Even before then they had been outsourcing but now they simply don’t own the profitable part of electric cars - the battery and power-train.
With or without the war in ukraine they would be disappearing.
The overall german economy is fine, there is increasingly unequal distribution of wealth like many western nations in recent decades, but the economy is ok.

Ps: I don’t recall the numbers for germany, but pre 2022 the EU generated less than 20% of their energy with fossil gas, and less than 14% of their electricity. Germany had a higher ratio, but definitely less than a third.