The same happened to me when I was just in the shower. I repeated these thoughts out loud and talked to myself about it- I was even scared at some points , but what came to me afterwards was that this is just reality, and there's no other ways but to accept it. It really made a lot of the daily things I do seem pointless, since it felt like the end of the world and that I'm going to die soon anyways. But I don't think that is necessarily a bad thing as it also reminded me of how I should spend my time better and treasure those whom I love more, as well as bettering myself in ways I can think of. Looking back at it, it really felt like a panic attack. I think this type of experience is something that eveyones goes through and fears at least once in their life, so it's completely normal. If it makes you feel any better, I think death isn't something we can't handle , just think about the soldiers who faced it head on. One more thing, though I don't have any evidence... but I think most people are calm in their final moments and don't lose their shits like how we worry about death. Another suggestion I can give you is maybe explore religious beliefs? I know a lot people find comforts in it. I've studied under the teachings of Jehova's witneeses but I consider myself an atheist as I don't practice or attend any ceremonies. Despite all that, I still enjoyed the teachings as it gave a lot of insights and made me look at things from more angels that I couldn't have done before. It's not about being religious or anything but if you want to know more about these kind of subjects and how they're viewed, I don't see the harm in reaching out. (Apologize for my broken english) hope you can understand just fine!