OCD over the impossibility of immortality?

I've recently been spiraling very often and very badly over the fact that death is final. This seems like an obvious idea, but I mean that I focus entirely on the idea that because the universe will inevitably end one day, there is no possibility of existence beyond my immediate lifespan. And then from there I start believing that existence is meaningless because it all inevitably leads to the same end, no matter what humans do, even past an individual scale. Believing in the possibility of uploading human consciousness into technology in the future is already a stretch, especially adding in the idea that a random person like myself could somehow be brought back even after death, but it was a comforting thought that stopped living from feeling like a finite countdown to the end. But now that I've started having these spirals, I've ended up entirely logically deconstructing the concept of free will and the meaning of existence. During these times I don't even understand why I should bother trying to improve the world at all past my immediate experience, since I won't be around to experience it and it won't build to anything but the end of the world. Everything feels futile and fake when faced with this realization. I think a big part of it is that I feel like I don't have enough time in my lifespan to experience everything I want to. I wish I could just continuously exist forever with constant new things to read or watch or write about. I know this sounds more like depression, but the spirals last 5 or more hours and I cannot do anything except think about these concepts during them. I already have pretty severe classic contamination OCD that is triggered by very specific things, and I'm concerned that my OCD might no longer be confined to that theme.