Hello
IMO it sounds like the depression symptoms may be from the the psychosis episode you're having. When you've experienced something like this before what helped you move on from the psychosis? It seems that when the delusions are stable the other symptoms improve as well over a period of time.
Also the possibility of the world ending in our lifetime is small. Is there something that gives you this impression that is refutable? It may be helpful to find ways that this thought process could be redirected.