I'm going to ask my dad's girlfriend to leave while my grandad was dying
Why would you ask your Dad's girlfriend to leave?
It was my grandad, he deserves to be alone with his family
You should let your grandpa decide who he wants to be around. It's not okay to make assumptions about what he wants. Maybe you should check in with him before asking her to leave.
Fine. What would you have done if you were me?
I would ask my grandpa what he wants before making assumptions. He might want your dad's girlfriend to be there. You won't know unless you ask him.