I created an account just to "like" this, dorky as that sounds. You nailed it. She forgave the others because they're cool and in the in-crowd, and Jennifer's not. And yet Jennifer stood by her when no else did. If that doesn't reflect Kathryn's character - or lack of it - i don't know what does.
Even more repulsive and frankly terrifying was how she treated Jennifer after Jennifer had her baby. The poor woman was in tears, saying "So are you even going to ask about my baby," and Kathryn just glared at her, ice cold. She's disgusting.
How about Naomi casually commenting, "Oh, I didn't even care that I called her an escort, because" blah blah blah, all airy and dismissive. And then Ashley looks at her in shock, and Naomi just says "What, why are you looking at me like that," like she's something on the bottom of her shoe. Ugh, she's a B.