Me and my insecurities

Few days go by that I don't think badly about myself. I have this constant need of attention from some few people to remind me that I am worth it. All comes down to it. I cry for no good reason. It is not that I am not important, but there is always someone else more important. I am just the substitute, the spare tire to use when the other one is broken. Homeless dog syndrome. I start feeling left out whenever something happen that I don't get to know upfront. In my head I hear that I was never worth a dime and I see no reason to keep going. I get the seed and make it grow until it overtakes my head. When someone shows any interest in me, I ask myself how, why. How can anyone like this piece of shit they see in front of them? Asking the question just keep everyone away, but the neurosis of knowing the answer as well. I try to rationalise and tell myself it is nothing, but all I come up is the question of how I survived so far...