"By hiding it for him, you're also part of it," Mercury points out. Howard shares in whatever guilt exists here. "And even if you call it an accident, someone is still dead."

This may seem like a somewhat harsh analysis, or certainly a moral one, but really it's just her own guilt: whatever her reasons, those events still happened. She can tell herself the reason makes a difference, but maybe it doesn't, especially when the motives are all mixed up.