Let me just say, that while people are calling Snow out on what she admitted in the cave, I feel like people might be blowing out of proportions just a little bit.
She wasn't saying that Emma wasn't good enough. She was coming to terms with her own reality. She WAS cheated out of the life she should have had with her daughter, and she recognizes now that it is a unique and delicate relationship that she has. Yes, Emma is her daughter. But Snow also had to sit and watch her daughter admit that all her life she had felt like an orphan because of the life she had been unable to have with her parents.
She's not saying that Emma wasn't good enough or that she wasn't going to try and mend and allow her relationship with Emma to grow. She was merely stating that she wanted the chance to be a mother, to have a different experience, and to have another child, as well as to maintain the relationship with her daughter. I don't think that really makes her terrible. This situation has been difficult for everyone, and calling Snow out on it isn't fair, when everyone has had their share of heartbreak. She loves Emma, she loves her family. But she's also incredibly nurturing, and has a desire to care for someone, and the fact that she didn't get that chance with Emma, and the fact that Emma doesn't really need or want that now is hard for her. I don't think the desire of having a second child negates the relationship a mother has with her first child.