I gave my 8 year old niece an X rated movie for her birthday
That's disgusting. How do you think she will reaction from seeing an X-rated movie?
What do you think? She's 8!
You shouldn't have given her a porn movie because It's pretty messed up to expose your eight-year-old niece to that at such a young age. It's going to mess up her mental health and innocence. Also, her parents will start asking her questions if she exhibits certain behaviors and they will probably beat the living daylights out of you.
I'm trying to teach her about sex so she doesn't do it on a rebound.
It is a crime to give children pornography. It also might be suspicious if people knew what you did like you were trying to groom her. Sex should be taught by her parents.