@inflib (Donna): Dealing with people could be unsettling, but of course it is impossible to avoid. So, one just do the best one can. I think you are doing the right thing. If you try to “reason out”, it may lead to aggravation and escalation.
You said: “I’m concerned that silent may cause the niyata micca ditthi person to act out even more, but I do not want to lie just to make that person stop.”
In Buddha Dhamma, the true intention (cetana) overrides anything defined in the conventional sense. “Musavada” in Buddha Dhamma is NOT “lying” in its literal sense.
During the Nazi terror in Germany, many Germans “lied” to the Nazi’s that they were not hiding Jews in their houses; of course the intention was to save human lives and thus it was the right thing to do and it was NOT musavada. They acquired good kamma for protecting lives.
We need to realize that “lying” — as meant in as “musāvāda” in the five precepts — really means the “intention” involved: “Musā” means “wrong or incompatible with morals” and “vāda” means “speech”.
-Therefore, even though they were literally lying, their intention was not a “musāvāda“, but actually a “good deed”.
Let me give an example from the Tipitaka.
The Buddha asked his brother-in-Law Nanda to become a bhikkhu on Nanda’s wedding day, before the wedding. Prince Nanda was to get married and become a King too, the same day. Nanda could not say “no” to the Buddha out of respect. After becoming a bhikkhu, Nanda kept thinking about all that he “missed out”. Then the Buddha took him to a deva world and showed him the female devas, and asked whether his bride was better looking than them. Nanda replied that his bride looked like a “burned monkey” compared to the female devas. So, the Buddha said Nanda could get access to such devas, if he followed Buddha’s instructions. Nanda agreed, and soon attained the Arahanthood. Of course, he realized well-before that nothing in this world was better than Nibbana.
The point is that the Buddha saw Nanda’s ability to attain Arahanthood. If he got married and became King, he would never attain Arahanthood. Rather, a king is very likely to be reborn in the apayas, because of the things that a King has to be involved with. So, what the Buddha did was to save Nanda from all that suffering.
A Buddha, by definition, cannot utter a musavada.
So, I hope you get the point from this story. One needs to act wisely according to the situation at hand. Obviously, the Buddha handled the situation that way, because he saw the potential of Nanda to attain the Arahanthood. Also see: “Right Speech – How to Avoid Accumulating Kamma“.
By the way, what Tobias is saying about “heat in the mind” is tāpa, which is addressed in the Satipatthana Sutta: “Satipatthāna Sutta – Structure“.