I forgot about Greydon. :/ but I do like his Stockholm Syndrome.
anyway, I'm not sure what advice to give. I don't like outright lying, but if there is a possibility of being disowned I don't suggest the complete truth. Maybe you could somehow gradually tell him. I don't know, Try picking the stupidest thing he believes and be like "I don't think that make sense because...." Or something. Not sure if that is a good idea, but it's all I got.
anyway, I'm not sure what advice to give. I don't like outright lying, but if there is a possibility of being disowned I don't suggest the complete truth. Maybe you could somehow gradually tell him. I don't know, Try picking the stupidest thing he believes and be like "I don't think that make sense because...." Or something. Not sure if that is a good idea, but it's all I got.