I would suggest they did not decide to be bad parents, but simply didn't recognize the need to do better. It's not an excuse just a truth. Children learn from their parents one way or another. The person you are when you entered this realm determines the way you will interpret your lessons; to mimic or be the exact opposite.
I too chose to be the exact opposite in many ways. My forgiving my parents for simply being who they are (and I in no way suggest I have experienced what you have; in no way would I dare minimize your anguish and hurt and experience of abuse) allowed me to find a happy medium in many areas of my life.
Holding on to the anger slows us down and keeps us from finding solutions for ourselves.
Please believe me when I say, I wish forgiveness because it helps YOU heal. It is your own, personal, and true blessing; the best gift you could ever give yourself.
Forgiving them empowers/liberates you to separate your intentions from theirs. It lightens the burden of their control and makes you lighter and stronger on your way out of the abuse.
My heart is with you.