Your post was written perfectly and I definitely felt your frustration. Many if not most of us here have had to suffer through the same or similar behavior - I certainly did with my mother and brother. My mom would actually get heart palpitations and hypertension everytime we engaged in similar conversations.
The problem is they are so hopelessly dependent on the bOrg to think for them, decide for them and literally dictate their lives to them. The longer they are "in" the more intellectually lazy they become, common sense plays a smaller and ever diminishing role in their lives as time in the cult passes.MThey become so mentally incompetent that they panick when they are being challenged. Truth, facts, relationships, unconditional love are all decided by the bOrg and they will fight tooth and nail to protect their dependency on the bOrg drug. As LisaRose said, those hopelessly hardwired to the bOrg will only snap out of it when their thought process changes at the critical time, however that may come about is personal and no amount of arguing, evidence or even love on your part will change that.
You only yave one hope my friend - time. Only time will offer them chances to break free. In the meantime, don't give up hope and concentrate on finding your own happiness and success.