I think it is perfectly believable for Regina to still love Cora no matter how irrational it looks to us from the outside. Deep down, we all love our mothers and want to be loved in return no matter how much hurt they bring. People rationalize with themselves all the time. Regina had a major complex- that is why she blamed Snow White for Daniel’s death. She couldn’t bring herself to blame her mother- her mother’s hold on her heart was too strong. Psychologists deal with issues like this all the time. My dad has written a book on the subject. It’s called How Dysfunctional Familes Spur Mental Disorders.