Honesty is the best policy.
YOU are the head of your household NOT your dad. Just say that you have serious doubts about the GB arm yourself with a good agruement! I know you are risking DF but I dont think you can avoid it unless you start going back to the meetings like a good little boy! You have almost teenage children and you seemed to have made a family decision to fade, Say that where you had not much choice as to which religion you was raised in as a child, you have a choice as an adult.BLAH BLAH BLAH. Be strong, be firm, be a MAN!
GL