Why would Russia use nukes on Ukraine?
Is Russia losing their conventional war so badly that they have to use nukes? Against a non-nuclear nation?
Seriously, if they do this then the year 2100 will come and go and Russia will still be a pariah state. If it still exists.
The west is already doing everything they can to make Russia a pariah state. What would they have to lose? They would still have the same Allie’s they do now.