Shame is a very old coping strategy, usually developed in childhood.  When children don't feel safe expressing their angry feelings, they will try to manage these big emotions alone by turning the anger back inside and by being cruel with themselves.  Shame is anger turned inward toward the self, and it is the most toxic of all the emotions.  

Almost every other emotion serves a useful purpose.  Guilt means, "I did something wrong."  Guilt surfaces when our morality is at odds with our behavior.  If I steal a candy bar, I leave the store feeling guilty about my actions.  I know I have done something wrong.  Guilt is useful because it helps us improve our behavior: guilt helps us navigate between right and wrong.   Shame serves no purpose, because it puts us at war with ourselves.  When we feel shame, we feel like a fraud no matter how successful we are.

When shame blinds us, we can see nothing good about ourselves.  Shame tells us, "I am something wrong."  Shame tells us, "I am not good enough."  When we struggle with shame, we are convinced that we are hateful and undeserving of love.  Shame creates a force field around us that lets in only the negative data and rejects the positive.  We are so obsessed with our darkness that we feel incapable of tolerating other people's attention and affection.  Shame isolates us.  I personally know how lonely it can be to struggle with shame.  I don't want you to be alone, and I would like to help if I can.