Lizzy31, do you have the resources to move out? That would be your best bet.

Can you afford a therapist? I think seeing one might help you to be able to insist that these folks treat you like the adult you are, and you will be able to speak up, too, when you are not able to be "nanny on the spot." They are doing it because you are allowing them to.

I see a therapist and I have been able to learn to speak up for myself when I need to. It's really empowering.