How are you supposed to overcome the inevitable?

I get it, im insignificant, when i was little i thought i was this main character. Now as a 21 year old I realize im nothing , I will die, my family will die and I will suffer. Life is beautiful but ina way meaningless. it doesnt matter what we do. I could kill someone, commit a really bad act, what will happen? Besides me facing the consequences and the person dying I wont cause a blackhole? The earth does not care. (i will not do this, its just an example) I have this empty hole in my heart that I know is the dread of nothingness and death. Ik i wont care once I die but life is all I know. Ik its my ego that cares but man im past the stage of a good life , 20+ is all going downhill, age wise, deaths. I cant imagine my grandma being in nothingness. I hate how people dont realize and take their life for granted. But i have this hole in my heart that i will never ever fill, unless the afterlife can be proven. I get why people are alcoholics, if I wasnt living with my mom I would probably become one. Smoke cigarettes all day and just wait for my time.