Welcome, Aunt Connie.
It's important to remember that this is a cult, but it is a cult with benefits. The benefits to the 'cripples' as you put it, and the needy can be quite large. These are the people that will feel less compelled to research this cult and leave, because if they do, who will snake their toilets?
As time goes on, those that are needy will outnumber the able bodied members, and then you will know the true joy of Christian love and giving of yourself! I am pleased that your parents, in their old age, have stepped off that treadmill and are getting some rest from it. Stop blaming them for your situation, dearie, cuz you're all grown up now, and you have resources. You are here! It's a good start. It's sad that your apprentice is in her 90's and wasting these precious last years knocking on doors. You should send her home or take her to lunch. Stop dragging her around.
You want your husband to stop being the go-to guy? Speak up. Get off the roles. Misbehave. He won't be able to control his own household, and therefore will not qualify as an elder. As it is, you only enable this disfunctional cycle. You can only control what you do---so either be happy with it or change what you are doing. Or be miserable, because that is a good start.
This organization will use you up until there is nothing left, and then it will throw you away. Stay at your own risk.
Be angry, but let it motivate you! Be critical, but turn that criticism on the organization itself. A codependent person will always help, but then feel bitter about it afterward. Help if it makes you happy, and say no if it doesn't.
By coming here, you have taken responsibility for your decisions. If you stay, their sickness will become ever more evident.