Well, when Cat married Ned, she was promised (And had feelings for?) his older brother, who then died. So Ned took his brother's place in all things, including the betrothal. If I remember right, it was even an old fashioned thing that he did. When he left, Cat barely fucking knew Ned. I mean, I can understand it I guess. He'sherhusband now and all, and she was pregnant when he left, but sheeshus. A dude who was practically a stranger went to war, and got an extra kid out of it. The fact that she transferred all of her hatred and anger onto Jon for that betrayal was fairly fucked up. The only one who doesn't give two shits is Sansa because she is a bitch. The rest of the kids + Ned are like, bitch you are tripping. And yea, it was a betrayal. Jon was Lyanna's kid, and it was her dying wish that he protect that baby. The only way to do so was to pass it off as his kid. Robert might have been vindictive enough to kill a child because he regarded it as the rape of his intended. So it wasn't like Cat ever knew the real story.
Also, she DOES do things out of love for family, but it's fucking stupid shit she does. I've said this before, but it's not like what Ned does - Ned made bad decisions and often underestimated people in various ways, but Cat was the opposite. I am fairly sure once she went down that road of "I am going to get justice for Bran" there was an actual comment about her saying how ruthless the Lannisters were and yada yada, and yet STILL she went ahead with her crap.
I pitied her a lot, because I understood it was for love, and to protect her family, but she went into those situations with the full knowledge of Lannister wrath. Maybe she thought if Robert was still alive Ned could talk to him, or something, but I was quite angry at Cat for a long time because so many paths led from her initial decision and they all ended poorly.
Those things aren't technically her fault, and let's be honest. How many of us would have been like, hey, I should probably not do this because I might get my ass kicked? (I would be a total pussy and just fucking hide though for real.) The *only* small piece of argument you could make is that she wanted to make sure no one was sent to try to kill Bran again, which it SEEMED to start out as, but then on her way back she just takes Tyrion. SheknewTywin would never stand for such an insult to his house. She takes him to the Eyrie, where she gets pissed at her sister for failing to keep Tyrion, but it didn't matter. Just taking him did the damage, and she had to know that.
I don't super hate Catelyn, but I have a very hard time feeling a whole lot of sympathy for her when she went into the situations with a lot of knowledge. In the book she tells Ned to be Hand to Robert because she is worried the Lannisters might have something to do with Jon Arryn's death. Someone who legitimately thinks a high ranking family murdered the second most powerful man in the kingdom is not the sort of person who should turn around tomorrow and decide she is going to be a one man crew for justice for her family.
