I’m terrfified of death and dieng

I’m terrified of death and dieng and it is affecting my life and mind quite a lot. I get myself into a worry and panic when I think about it, about how one day you’d suddenly gone whilst the world goes on forever but I’m also terrfied of dieng... I think seeing people around me die has triggered it, one of my school friends age 21 years old was found dead in his sleep last week and I have been thinking about it non stop and imagining different stuff . I get scared to go to sleep incase I never wake up and I will never touch a cigarette again or anything like that because I want to risk my chances, I also get scared someone will kill me for example I check all my doors are locked as I get into bed as I imagine someone being there. I always do stuff like that. I always have the worst scenarios in my head too for example when I go on a plane I imagine it crashing ect I know this can sound ridiculous but it’s destroying my mind and I don’t know how to control it. Because once I think about it. Effects my mind so much ☹️