What's up with Grace?

First off I should say, this movie does not follow the book very well. It cuts out quite a bit of the story. I would recommend the 1983 BBC version with Timothy Dalton, at least for now. There is a brand new version airing on Masterpiece Theatre in January 2007 that looks quite promising. Being a fanatic of the book and having been disappointed by many of the film and TV adaptations, I am hoping for the best. Anyhow...

Grace Poole is the caretaker, not the mad woman. The mad woman is Bertha Mason Rochester, Edward's wife whom he married when he was nineteen. In those days, divorce was not allowed unless one could prove adultery. Anyhow, it was Bertha who set the fire - she escaped from her room when her nurse was asleep, and set the curians on fire. Rochester didn't fire Grace for several reasons -
1. Getting a nurse to care for someone like Bertha was difficult and expensive. Not that he couldn't afford it, but...

2. If he had fired Grace, and replaced her, it is almost certain that his secret about having a mad wife in his attic would have gotten out to everyone, including...

3. Jane. By the time of that fire in the bedroom, he was already madly in love. He states in the book that he loved her from the first. That is why he wants to keep his first marriage a secret - cruel as it seems, he doesn't think of Bertha as his wife, but as a burden he's bound to for life. By keeping her identity secret, he hoped to marry Jane and find happiness.