Because there is nothing to forgive, no mistake to forgive because you didn’t do anything wrong. You were the victim of abuse. We tend to make excuses to defend the abusers by saying that it was our fault that they abused us, because the fact that people we care about abusing us for no reason is unbearable. So we make those “reasons”, we try to make sense of their behaviors using a wrong logic to protect our feelings. I see you as a strong person, the only thing you lack is a correct type of therapy and supportive people around you. If I can recommend, try to listen to some podcasts about how to heal a childhood trauma and how to love yourself. Be your own best friend, parent your inner child, be someone you wished were there when you were a child