Yeah, the heightened potential for nuclear annihilation is terrifying but there’s frankly nothing you can do to survive it. Even if you somehow lived though the bombings, there’s no corner of the globe where starvation nor irradiation would not reach. The Earth would be uninhabitable and death would be certain for most land animals.
It’s a tragic way to die and for the human race to cease to be. But it’s only death and that’s certain to happen one way or another. There are countless other ways you could die that are either within or beyond your control. Many are far more likely to happen than nuclear war. Do you fret about being killed in an accident every time you step into a car?
I know it’s a lot easier said than done but try to live in the now rather than the future. Plan for tomorrow but recognize that, unlike the present, the future is not guaranteed. Don’t take the present for granted, go do things that bring you fulfillment now because ultimately that is the only time that you have control over.
It’s certainly plausible to survive the initial bombings by taking adequate shelter, you may even be able to stock up enough provisions to survive for several months. The problem is what follows.
Nuclear winter is hypothesized to change the climate to the point where growing food is impossible, potentially for several years. Any animals you can hunt before they eventually succumb to starvation will have been poisoned by the fallout, their meat contaminated.
The fallout will spread across the globe, making the air you breathe toxic, either by radiation poisoning or by any number of harmful construction materials such as asbestos which is now particleized and floating freely.
If by some miracle you do still cling to life by this point, you will either be completely alone or surrounded by people just as desperate to survive as you are. Only in fiction do either of those situations end well.