Delores Claiborne changed from the timid woman she was when she first married to a strong woman willing to stand up for herself and murder her husband.
Although her story is told in flashback, we do get the idea that Delores the housekeeper is different than the Delores of her youth. As a housekeeper she is old and cantankerous, but the change is more than that. She made the decision to kill her abusive husband, and that changed the rest of her life.
Delores is saucy and self-assured. Being questioned by the police does not seem to bother her much.
I got an idear you’re gonna be listenen to me most of the night, so you might as well get used to it. (p. 19)
She swears that it did not turn her into a killer. She did not kill her employer. She killed her husband because he as an abusive, violent, and dangerous alcoholic. It’s a fact she freely admits.