In general, my approach to dealing with such people is to stop talking about what's really true, and instead talk exclusively about what experiences I anticipate if I perform various actions.

We may not be able to agree on whether there's really a hammer in my hand or not, but if we can agree that if I do something I experience as swinging this hammer at someone's skull, the other person will reliably experience having their skull hit by a hammer, then our disagreement doesn't matter much.

Of course, as you say, ego gets tied up in having other people talk about the world in ways that match my preferences.
I try to reject that when I find myself doing it.