I've heard of lethal injection but this is ridiculous.

From what I've seen, depending on how you complete the game, it's implied after locking herself in the True Lab she commits suicide. Granted she's made a number of mistakes, but it takes more than a little guilt to push someone into taking their own life.

The amalgamates are her biggest failure which is why she has no self esteem or confidence. I mean, the families of the amalgamates still deserve to know what happened, but I'm not sure she could tell them without going through a mental breakdown.

Also, she didn't know that the flower from the surface had been imbued with Asriel's essence, so I can hardly blame her for Flowey's inadvertent creation.