Whether you decide to tell someone you are carrying in their home is one of those ethical questions that only you can decide.
I'm more concerned that you would so easily allow yourself to be disarmed. I mean, you have decided that the world is dangerous enough that you have made the decision to go armed. You are prepared to use deadly force to defend yourself and your children if necessary. Yet suddenly, when you arrive at a friends home who is afraid of guns, you are willing to sacrifice yourself and possibly your children and become another helpless victim.
There is nothing noble about being a willing accomplice to your own victimhood. (not sure if victimhood is a real word)