how to deal with intrusive thoughts about death

hi all, i've constantly been thinking about death and the whole nothingness that comes after it. it is so annoying because on the conscious level i am not afraid of death, it just makes me sad that it is forever and a state of existing that is infinite. i just cannot stop thinking about it, i think about it multiple times a day, i imagine my friends and family dying, i imagine myself dying, sometimes the scenarios in my brain are super graphic and disturbing, i always imagine the worst case scenario in every life situation to end up dying. and i do ERP and i accept that death is a fact of life. but i cannot get the thoughts to stop. and they have been affecting my dreams, with me often having nightmares about myself or my friends and family dying or about something coming and wiping out all of humanity. what else can i do to help myself heal?