The backwards spiral of existentialism

It was a wonderful party and I was enjoying myself, celebrating life and joy and marriage. It was then that I was ambushed by despair with a simple passing thought. "In 50 years most every adult in this room will be dead, probably including me."
Moments slip into hours into days into months into years and the wrinkles around my eyes deepen, the skin on my arms looses its elasticity, and my daughters look more like little ladies. Our grandparents were married once too. They too were young and in love. Like my husband and I they had little children and felt all their lives were before them, standing tall and proud, arm-in-arm against the onslaught of time. During their lives they faced wars and economic depression. They were full and busy. They had sadness and joys and they loved; they loved their children with the same fervor with which I love my own, they felt the same passions for their spouse, the same longings for safety and peace, financial strains and maybe even the same fear of death. Did they lay in bed together and discuss the possibility of another baby? Did they argue when what they really just wanted was to be held? Did they cry together over the death of their own loved ones, just as we have cried together over their deaths?
These thoughts are the strong undertow that pulls me down, down, down the backwards spiral of existentialism. At first I am enjoying the swim, immersing myself in the present moment and then I am being pulled under by the strong current of time, awash in the meaninglessness of it all. "Eat, drink and be merry for tomorrow you die." Tomorrow you die. Tomorrow is coming and one of these tomorrows will bring death. Is death a door into eternity or just the infinite blackness of nonexistence?
I don't want to give into the blackness. I am going to fight my way back to the light. Where is the light? I am suddenly so cold inside my core, so full of sadness and sick from fear of the loss to come. I don't want to grow old and have my children take my place as the parents. I want to fight to the end, but why? Does it matter?
That is where despair finds me, my old foe wearing his muddy garb, ready to pull me down into the depths of all that meaninglessness.
"No" I mutter inwardly "No, I will not let this happen. This is precious and I will not surrender this moment."
"Please Lord, help me. Pull me out of this blackness; out of this fear and unknowing. I need your help. Show me your way of looking at my life."
Immediately I feel myself being pulled out of the blackness back to the light. I put my head down against the weight of time and will myself back to life and away from thoughts of death. When I comes I will be ready, but I will not waste what I have been given by falling down the backwards spiral of existentialism.
I am standing upright again, my head above the water, both feet planted firmly on the shifting sands of time that will invariably pull me into the future. I take a breath and fill my lungs with this moment. Only seconds have transpired since my initial thought, the initial shove backwards. Only a few breaths, a few blinks of my eyelashes, that separated for me the light from the dark, life from fear of death, joy from sadness.