The type of end-of-the-world situation that's making you so frightened is really, really unlikely. The type of scenario you see described in the papers etc is usually the worst-case scenario because it gets people clicking. Intelligence even shows that there are no signs that Russia has made any serious preparations to deploy nuclear weapons. I think it's really important to remember that ramping up the fear factor is a tactic to get people in NATO countries to waver, and mentioning that particular word is a good way to stir up that fear. This doesn't mean that something is actually going to happen.
This. Also, whenever I get anxious reading the headlines I try to remind myself that 1) if Putin was a madman who just wanted to end the world for no reason he could have done it ages ago, there'd be no need to invade Ukraine and make loads of theatrical threats first, and 2) he clearly doesn't want NATO getting involved (which makes sense because in terms of conventional military power the NATO countries combined are much stronger than Russia on its own).
I went into this a bit more on another thread, but it seems to me that he's intentionally timed this invasion for when there'd be very low appetite for military involvement by other countries - post-Covid, Trump out of the White House, lots of internal division in UK and European countries that was partly caused by Russia itself, etc. The absolute last thing he'd want to do is drag them into the conflict unwillingly, by launching an unprovoked attack on a NATO country that's not currently involved - particularly one like the UK, where, bluntly, other NATO members can't dismiss it as "just Eastern European politics, let them sort it out themselves". On the other hand, it makes total sense that whenever anyone from those countries shows a bit too much interest in military action he ramps up the "I'm an unstable madman with nuclear weapons, yknow" rhetoric to scare them off again. And then Western media runs with it because they're desperate for user engagement.