You have to keep us updated on this one! Congrats for sending the email. My mother does the same thing (silent treatment) when I tell her something she doesn't want to hear. I find it very annoying because it is so manipulative.

Now that I recognize it as a manipulation tactic, I find that it just strengthens my resolve.

This is a win-win for you. Your mother may cancel her trip to punish you (ha!) or she may decide to accept your offer -- but now she knows that she will not stay with you.