I don't want to tell my fathers family why he's in a coma but I need to ask them something.
What is so important for you to ask them?
I want to ask them how they feel about deciding if my father should live or die.
You're probably scared of how they'll react and that's perfectly fine but you shouldn't keep it from them. It could affect choices in his medical treatment and you may be hurting his chances by not telling them. More importantly, they're his family and they really should know.
Wtf\ are you going to tell them?
I am not going to tell them anything, but I am urging you to! You should be truthful with your family about your dad's medical issues.