That Catelyn scene caught me off guard a bit when it happened. But I think your co-worker might have missed the end of it or something because what she says is:
1) She prayed for Jon to die because he wasn't hers and she was bitter and angry,
2) Then he got very sick, and she thought it was her fault for praying for his death (clearly she thinks her prayers have influence), so she felt guilty and prayed for him to live and promised she would love him and treat him as her own if he lived.
3) He did live, but she was unable to follow through and love him and treat him well even though he was an innocent, mother-less child (we already knew this part given how she treated him, this is what I mean about your co-worker not hearing that part)
4) She thinks the gods are punishing her family as a result of her not living up to what she promised them when she prayed for him to live and for her being too heartless and too big a bitch to love and treat an innocent baby well.
To me this painted her in a more sympathetic light because in the books she never showed any remorse for treating Jon badly. That will help TV audiences feel more upset when the RW happens, and the RW will be more impactful if they view her a litle more sympathetically than book readers. Seems they are playing up Robb and his wife more as well for that same reason.
So I think it rings true still on how she treated Jon, but not so much on how she felt about it because I never got any sense she felt guilty about it in the books. Of course here she only feels bad about it because she thinks it resulted in bad karma and problems for those in her family that she actually does love. She'd have no remorse abot it otherwise, I'm sure. She seems to actually think her bad acts resulted in bad karma. Little does she know what's coming!
The other main reason for having that scene in the show is to get viewers wondering who Jon Snow's mother is and to keep that topic in mind since they haven't dealt with it much like the books did.