Mensonges: What is a Lie Worth?

I do not know what to do. Monsieur Tallman wants for me to swear au nom de ma famille...
 
He wants me to swear on my house that we will leave and that we will tell no one what we have seen. I cannot control this. I am 18 years old. Who thought it was a good idea to put me in charge of this?
 
What would grandmère do? Maman would not want me to bring shame to la famille. She has done so much to legitimise the house. Or at least, that's what she says. And she would care about the lives of the foresters, but...but we sent word anyway to the Bagir'...maybe someone else could deal with this. Maybe there is a way that does not break a vow.
 
Mais grandmère, que ferait-elle?
 
If this is what Monsieur Tallman is doing here, why would he hesitate to do it elsewhere? What is the oath worth if he is forcing it? If this is how he treats us, what would he do to the foresters? What will he do to the lizardfolk?
 
Merde, my head still hurts. I'm never drinking again.
 
Who is he working for?
Why is he building a...forge so far from his home? Where is the rest of his family? Do they know?
 
Maman, I wish I could ask you, but you are not here. What use is having a house, what use is nobility if you can't use it to help people? I do not want to see anymore death.
 
It's not just the foresters, or the lizardfolk - what about those who work for him? They will have to fight the lizardfolk. The lizardfolk are huge, but Lucas says a lot of people could sleep in that room. They would be overwhelmed, and there would be a lot of bloodshed on both sides.
 
Maman does not like lying, mais grandmère...if the lie could save lives...why would the house be of importance?
 
I really hope I'm making the correct decision.