Towards a Sense of Security . . .
Perhaps my experience of growing up was not as extreme as yours. But my family, I feel, contributed to a deep feeling of low self-worth. After working through the 12 steps of AA and gaining a conscious contact with my higher power. I learned how to forgive, not only those who I felt had harmed me, but myself as well.
Forgiveness, for me, is closely tied with acceptance. I cannot change the past or other people. I find it more healthy to accept the things, and people, that I cannot change. Then forgiveness allows me to free myself further by getting rid of my blaming attitude and resentments.
Perhaps more importantly, I need to accept myself and forgive myself. Sure, I can change myself, but first I need to accept myself.
Forgiveness was not easy for me, at first. I had a hard heart. Only with the help of my higher power, was I able to let go of some of the hatred of the past, caused both by my actions and by others' actions and begin to forgive myself and others.
Trusting a higher power, acceptance and forgiveness may be the first steps to that elusive sense of security. Not for everyone, I know, but they work for me.