Russia is in terrible shape. Their military is a shambles, their equipment is garbage and poorly maintained, and their nuclear arsenal is just as bad. They couldn't launch most of it even if they wanted to, and would likely accidentally nuke themselves if they did.
Putin vastly overestimated his military's ability and equipment (he thought he could take Ukraine in a single day - it's been 2 weeks). Now he knows better, which is why Russia has been barking so loudly instead of acting, threatening everyone under the sun, saying "X is an act of war", "Y is an act of war" etc etc. You only bark that loud when you've got nothing to back it up.
There will be no nuclear armageddon. The Ukraine conflict will stay there, the rest of the world will funnel in arms but not soldiers, and Russia will tire herself out over the next months/years fighting an expensive insurgency just like they did in Afghanistan (except they're in even worse shape now). And America and Europe are perfectly happy with such an outcome because it's a cheap win for them, which is why they're dragging this out.
Stop worrying and get back to your life.