Wow. Well, this is definitely unpleasant and slightly uncomfortable, but not unrealistic by far. You can say it was her attempt at trauma bonding that didn't go well (it rarely does), and that last thought she had ("He shared his dark past with me, it means I'm special!") is something I'm kinda familiar with, too. Embarrassingly so.
I agree with the statement that has been repeated in the comments throughout these chapters: they are teenagers who still have no idea how to handle these topics. Heck, most adults would be happy to make Kaede's confession all about themselves...
I'm getting quite a few red flags here so I can't say I like this girl, but she can still grow and learn. Most of all though, I just want our boy to be happy :c