You know, youth, immaturity and emotional turbulence are not a defense. Objectively, they both made poor choices. Before I'm collectively burned at the stake I'll qualify that.
Kaede got swept up in his happiness, trust and fear and shared something an adult would have known not to share with a child.
Tsubasa... Where to start... Have a little more self-awareness before PUSHING for details of a trauma, and way to get overwhelmed by your own, frankly, f#cked up worldview and uncertainty and attack the victim compounding the trauma...
That being said, for me it really demonstrates more than the mere setting the immaturity and emotional struggles inherent in the characters. I don't find her particularly evil, if solely because she isn't an adult, that doesn't mean I'd be heartbroken if (as someone suggested) she had a Zombieland Saga level encounter with truck-kun.
I think the recovery from this, IF there is to be one and if its to be done well, has the potential to be some of the better writing I've seen in manga.
I hope it's done well, without shortcuts.