I don't think NATO will go nuclear. They destroy too much more than their target.
I suspect that NATO would use planes, missiles, drones, and special ops to totally destroy what is left of Russia's army and it's ability to fight a war.
Then we will leave the to pick up the pieces.
These times are very frightening. There is chaos and power grabs by Nationalist parties and psychopaths all over the world . 40% of the US House of Representivies are ready to join that group.