I'm scared of the universe

So here is a quick "disclaimer": I know that the Buddha didn't answer metaphysical questions since it made no sense to him. He wanted to afaik limit/remove suffering as much as possible. Also I know that science isn't always right and is itself making up theories which more then often enough turn out to be false. Also I meditate a lot every day as in sitting meditation and all together mindfulness. Well now to my question: I somehow get scared of thinking how there was (according to science) a big bang and then I wonder what was before the big bang or where the space comes from that the universe takes up etc. I don't know why but especially these last days I'm drawn to think about it even though I know it doesn't help me in any way and even if I happen to know everything it won't change anything. Also another thing I think of is heat death. Which again I know is a story made up by science and then I ask myself is it really worth to do anything, live, help etc. anybody if in the ultimate end everything will be gone and does that maybe imply that all beings will reach paranirvana? And just like these questions seem metaphysical and paranormal I feel like the idea of rebirth and paranirvana is also somewhat scary to think about and is as well somewhat metaphysical. I wish I could give up all these unnecessary thoughts which cause suffering to me. Also I wish science wouldn't go as far as trying to explain everything. Do you have any thoughts on this?