I see it this way:
1. my parents caused me damage
2. sadly for me they were blind to what they did. And that included endless arguing - once my father threatened to crash the car on the highway with me and my mother in it.
3. But they really had no clue what I was going through.
4. God/ nature/ chance made them that way. They never chose to be that way, so ultimately I see them as awful, but not intentionally awful.
5. How to forgive? If I may quote the New Testament as wisdom (not religion): "they know not what they do." Of course that doesn't mean they weren't responsible. Just that they didn't CHOOSE to be people who allowed themselves to be the way they were.
6. Does that mean I forgive and forget? No!!!!!!!!! I carry the damage. But I know that it is the result of a pointless, random, miserable confluence of chance events (= them being my parents), thus the inner voices are like a broken leg. It hurts, it gets in the way, but it is devoid of meaning, of truth.
7. Is that forgiveness? It's forgiveness in the way I forgive a vicious dog that bites me. What's the point in holding a grudge against random bad things? The bite still hurts, I still dislike the dog. But not to forgive it, is to assume the dog knew it shouldn't bite, knew the consequences, and still bit anyway.
8. Forgiveness doesn't prevent me being angry. It just lets me feel I have a right to ignore the inner voices and recognize that they are mere damage; as I said, they're like a broken leg.
PS
Being damaged is a great way to make friends!!! It makes one humble, and anyway most people are damaged. It's actually something people bond over.