How can I possibly continue my life?

All my life I have been forsaken to have a destiny filled with eternal torment and grief. I never had true friends or a girlfriend. I never had the things I wanted most. Every day for the past 5 years have been like a nightmare knowing that every tomorrow would be another today. I hold back tears that my heart wishes to cry because I know I'll never have friendship, true love, and that my dreams will never come to be. I feel like its time I let go of my false hope and stop dreaming the impossible and end my nightmare. I've been on all sorts of medications for depression and seen many therapists but by sorrow pierces through the false emotion of happiness that those horrid medications provide. Nothing can help me or release the shackles that bind me to a fate of sorrow. My life is valueless and meaningless. I'm totally insignificant in the grand picture of life and hold no purpose. I know I'm worthless compared to everyone else. I'm like something that should be discarded. I found an undetectable poison that can put me into cardiac arrest and it will appear to be natural causes in the autopsy. My family will miss me but their pain will not be nearly as much as I would have had if I continue to live. How can I go on with my life when I don't have anything to live for? How can I live when I know my dreams will never be? Is life really worth it when the only path that I will walk is a path of eternal sorrow?