Brian -
Sorry to hear you have been treated this way. Please don't cancel. You will not have to pay the fees. She will. That's why she wants you to cancel.
Your host has made a mistake you shouldn't be penalised for it.
Contact BnB straight away through their customer service number and explain what has happened, The number is on your booking confirmation.
They should help to find you an alternative. They will be able to see by the messages between you and the host that she wants to double the price, then asked you to cancel.
Good luck