I don't recall details of the past showing that Derek purposely gave Kate information that he knew she would use to kill his family. They really aren't equivalent circumstances.
I downloaded the TW novel "On Fire" the other day and it goes into the Derek/Kate thing a little further. Omg there's also a page or so about the Stilinski's back when Stiles was younger and his Mother was still alive omg the feels! T_T
Anyway as for Scott's betrayal and Derek hearing him, is it possible this was part of a larger plan they'd formulated? I only mention that because I'd read an interview somewhere saying Scott had been forming a plan all season and it was about to pay off in the last 2/3 episodes. Also the way Scott just "found" Gerard's silver pillbox right by where Derek was standing? That may not be a fluke (or I hope bc I really like Derek/Scott's brother like relationship).
Anyway as for Scott's betrayal and Derek hearing him, is it possible this was part of a larger plan they'd formulated? I only mention that because I'd read an interview somewhere saying Scott had been forming a plan all season and it was about to pay off in the last 2/3 episodes. Also the way Scott just "found" Gerard's silver pillbox right by where Derek was standing? That may not be a fluke (or I hope bc I really like Derek/Scott's brother like relationship).