Look, we seem to do this wank every few months, but here's the thing. Whatever you think of Cat, her situation is not comparable with a "stepparent" is the real world, as in most stepparents choose to be so. If my husband would drag home a baby from lord-known-where AFTER we got married, ou can be our ass I'd feel no obligation towards that kid whatsoever, and a lot of resentment towards my husband. In normal circumstance, I'd divorce, but that's not so much an option in that world.

So no, cat is not a saint, but she acts about how ou could expect from most people in that shitty situation.