You're hired to test a machine that can see into the future...what you see is the end of the world, but you do not see exactly how it ended up that way.
The end of the world is a pretty big event. Not sure how any one individual could do anything about that. Especially when said individual doesn't know the cause.
As to how I would act, I'd spend as much time as possible with my loved ones.
Well, the world will end in some way or another whatever I do. And if I can’t see when or how it ended, what can I do to prevent it? It could be zillions of years in the future