Well we do know radiation exists within Chernobyl, while no one knows about aliens! :D
Panicking about WW3 is unhelpful and a waste of time and energy.
Putin is not after self-destruction, he's probably after a Soviet state that's self-contained and includes the old Eastern Block countries. And general causing strife and trouble-making because that's what he gets off on.
He's getting closer to China but the Chinese's greatest trade is still with the West. Despite the deterioration in relations between China and the West under Trump (who may well have been influenced, shall we say, by Russian money), China is still not going to lightly throw out that trade partnership.
Nothing, unfortunately, is going to stop the Ukrainians suffering because Putin's form of going to war deliberately targets civilians and vulnerable people in order to break the invaded country's spirit. He is a master of pyschological warfare with the tools of deception, fear and desperation.
Believing his promises is futile because he has no value for them. The only value, as far as he is concerned, is in how far he can get other people to believe him so that he can carry right on with what he's doing.
Whatever form of peace is achieved sooner or later he will keep on trying to cause trouble. I think the only thing that will stop him is by standing up to him and being aware of what he's doing by looking at his actions rather than his words. Presenting a united front towards him and no softness, no give because he sees softness as a weakness and good faith as something to be used to further his ends.
Panic is pointless and actually plays more into his hands than keeping calm.