[Nami doesn't know which time Katara is referring to, but it's moot. She holds her silence for a few moments, choosing what to say. And how to say it. Or try to say it.]

I don't... want them to see. How--

I guess I don't want to go home until I feel more like myself.

[It's only half an explanation. She sort of skipped the middle part. She can hear the fragility to her voice, and she hates it.

...and then she realises how that sounds.] Sorry. I shouldn't expect you to-- I just know you won't hold it against me, that's all. [Not being happy.] I can leave any time.

[You know what, that sounds worse. She'll just shut up.]