Who is Teresa Guerra from One True Thing and what is their importance?

Teresa Guerra is Kate's nurse. She stops by three times a week to monitor Kate's vitals and assist and to help her bathe. She is twenty-three years old, but is very serious about her in bathing. Teresa is from Ecuador, where she had a difficult childhood. She serves as a constant source of friendship and support for Ellen during the final months of her mother's life, as well as during the time of the trial.