I don't want to spend christmas with my maternal grandma
Why don't you want to spend Christmas with your grandma?
She's boring and I don't like being around her.
You should want to be spending christmas with your family members. You never know when they will pass away and you will miss them.
But I want to spend it with my dad's family.
Maybe you should try to spend Christmas with your maternal grandma, and your dad's family. I'm sure all of them would love to see you.