I think you and your mother might be conflating different meanings of 'truth'- i.e. she is thinking of MORAL truths, and you are thinking of SCIENTIFIC truths. The fact that I can test my beliefs against an objective reality tells me very little about how I should interact with my fellow man.
Anyone who reads a statement like yours who is even a little familiar with Ayn Rand would probably recoil, not at the actual words but at what they fear is coming next- 'reality exists therefore INSERT MORAL CODE HERE'. Unfortunately, we don't have your mother's response, but its possible when she was suggesting totalitarian dangers she was thinking along the lines of objectivism and other MORAL codes.
Moral truths which ignore scientific truths are invalid.
From Being a Realist (even if you believe in God):
My mother, who doesn't call herself a theist (I think she's agnostic), doesn't even accept realism. She doesn't even agree with this:
That's little more than tautologies here. Yet it elicited an impression of being forced to believe. I know because she told me about the totalitarian dangers from such narrow thinking.
I'm happy to have finally found the root cause of our ongoing disagreement, but now, how can I deal with that? It looks pretty hopeless, but just in case, does someone have a suggestion, or should I just leave it at that? (My ego doesn't like it, but giving up is an option.)
Now I'm relieved to know that in near mode, she's a complete realist. This craziness only shows up in far mode.