I'm going to scream at my grandma
Why scream at your grandmother?
I don't care about her anymore.
You should not scream at your grandmother. She helps to take care of you and it is wrong to treat family in that way.
I don't remember her doing anything nice for me.
Just because you don't remember it, does not mean it did not happen. You were a small child once, I bet she was helping your mother take care of you then. Just be more considerate to your family members.