It's okay, I agree with you on the "but" (very apt) part of it.
Yes, I think Jade does seem to be insecure about other girls attractiveness. But as soon as you start to argue with Jade you're always going to be on to a loser. Kate should have resisted even going there. But Kate did try to turn it onto Jade, you'd have to admit. Criticising what Jade does with her bum was irrelevant to the situation.
The insincere smile?
You must have seen it at times.
Alex has one that he did a lot to Jade, which was to dismiss her as ridiculous.
Kate's one annoys me a bit more. It's that totally innapropriate to the situation smile that looks very patronizing. It's done through gritted teeth to make out as though that person is taking it all lightheartedly, while underneath you can tell the person wants to rip your head off.
It's like a really sarcastic smile.
If you have the tape of the Kate/Jade row watch it with that in mind.
When people do that smile at me in an argument, my blood reaches near boiling point.