Don’t forget, Snow White probably harbors feelings of deep guilt over the death of Daniel (even though Cora manipulated 10-year-old Snow). So, Snow telling Emma not to blame herself for Robin’s death is likely Snow’s way of reassuring herself that she’s not to blame for the death of Daniel (even though she partially was).
The frustrating thing is that both of Snow’s extremes (deep guilt, blame absolving speeches) miss the point. Nobody wants a character to undergo constant self flagellation for all the wrong they’ve done. Guilt in and of itself helps nobody. It’s about taking responsibility and learning from their mistakes. Emma never seems to do that, and THAT for me, is the most frustrating part. Perhaps that’s also one of the (many) reasons why Regina is so popular. Instead of getting mired in self loathing, she’s used it to propel herself forward in a new direction.