why does dolores call her mother a saint?

Bernice is Dolores' mother. It's Bernice who tells Dolores that she and her husband, Tony, plan to divorce. Though Dolores lives with her mother at first, she is shipped off to her grandmother when Bernice has a nervous breakdown and is hospitalized. Bernice doesn't know how to handle the long-term situation when Dolores is raped at age thirteen. Dolores only perceives her mother is a saint to protect her own fragile phsyche.