Hardly in fact her 5.1 text gives us the exact opposite indication of this.
At no point after Theramore does she mention any desire to destroy the Horde she simply states that the Horde keep back stabbing her when she tries to bridge relations and as such see's no point in continuing to mend a relationship the Horde obviously doesn't want.
What do you expect her to do?
Honestly the Horde have blown up her city and now have started using insurgents in her new city, not to mention how the Horde in the first place obviously had no love Dalaran as they killed it's previous leader, nobody in their wildest imagination would continue to treat the Horde as anything but hostile at this point.
There isn't inconsistency. There's a character who wants to trust the Horde and keeps trying but they keep backstabbing her so she retaliates. Sounds reasonable.
You said you understood her going crazy, and yet you also in past said you wanted the old level headed Jaina back so you got it. Then the Horde betray her a second time, so she retaliates in a very very reasonable manner by imprisoning the guilty organisation. She isn't loopy.
---------- Post added 2012-12-07 at 11:30 PM ----------
[Arcane Torrent]