I want to slap my parent for letting my other one abuse me
Do you know if the other parent knew? This is very important.
I heard my mother whispering something about child abuse to my father and she never did anything to stop it
It is okay to feel angry at the parent who didn't abuse you if they didn't protect you. It is their job to protect their child and they failed you.
Nah, I'm going to stay calm and act mature about it. I'm going to kill them
You will be abusing yourself by doing that because jail time will be abusive towards you. Its best to just play it out and move on for everyone's sake, including yours. That way things can heal the right way.