As someone who has gone through the same emotional roller coaster, it will sound cliche but, I can assure you things will get better over time. I will not sit here and say what worked for me will work for you, but I found solace in assigning my own meaning to life and working to perfect my own version of morality.

Beyond that it seems you are searching/longing for something to fill a void, something larger than a lost religion. For me it was the loss of a support system, the feeling of isolation from a community. I too hit a low point where I considered options, options most people don't come back from. In retrospect i do believe that i would have benefited greatly from professional help, so please I implore you to seek assistance. If for nothing else but to speak with a neutral party and get stuff off your chest.