There can be no tit for tat mate. What do you suggest the west do as tit for tat, if Russia were to nuke Ukraine? Nuke a different bit of Ukraine?
No, we'd have to nuke Russia. And that is not tit for tat, it's a huge escalation which would risk the lives of countless millions in the west. It would be an absolute disaster.
I know that's not what anyone wants to hear but you cannot copy madman tactics when dealing with a madman.
Sadly, I think the best outcome at this point is that Ukraine falls quickly and with the minimum of further casualties, and from there we can continue to apply sanctions, to use all diplomatic channels and to try to negotiate some kind of compromise deal which may allow some of Ukraine some degree of independence.