Hideyoshi didn't betray Nobunaga. Mitsuhide did, killing (forcing into suicide) Nobunaga and his heir, Nobutada. That lead to a succession crisis within the Odas, and basically everyone trying to manipulate things to their advantage, but can't really say that anyone else outright betrayed Nobunaga.
Anyway, regarding this chapter: yeah, it's nice character development, but also ... the manga kinda loses it's edge with it? I don't know. Maybe it would have started to become implausible if she survived again and again while going on about wanting to die, but I'm not sure about this new direction either.