You deal with death by acceptance of the process of life.
There will never be a rise without a drop, never a wax without a wane, never an ebb without a flow.
We exist in cycles. Parts of your body are born and die every day. As you pace your floor worrying about your existance, skin cells are flaking off of you and turning to the dust on the floor you walk. New cells are dividing and growing within you at the same time.
Plants sprout and reach maturity and die, and go on to sustain the process of life by their consumption or decay.
Your mother's mother was born, created your mother, who created you, who will perhaps go on to create another, and another by them until humans as a race reach the end of life. When humans die out, our death will contribute to the further evolution of life on this planet. We die that others may thrive.
Stars are born, grow old, and die.. some stars explode magnificently at death, and their remnants coalesce to form new stars.
As above, so below.. As below, so above. There is a larger process going on all the time in this strange universe we live in. It is easy to see in part, but difficult to fathom as a whole. It's hard to realize that you are here, I am here, because a mighty sun died, because a million mighty suns died.
Have a child one day, and you will come to realize that you are not one life unto yourself, you are a chain of life, you are a link (Que Zelda music!)
This may not seem to help your grief right now. Loss is difficult and we are blessed and cursed at the same time by knowing the process. You are cursed to miss your loved ones, but you are blessed to know that without their, and your death, continued life would cease to be.
Find the glory of it. It's there, but of such massive scale that it's hard wrap your mind around it. Seeking this glory will reward you with great comfort.
Hang in there.
Snatch the pebble from my hand.. and you may leave.
(Sorry, had to make a joke...best of luck to you on your journey.)