Right. She vaguely remembers that if you want to last a long time without air then you have to be calm. It's actually very hard to be calm while your throat is being crushed. Probably being specifically terrified of suffocation doesn't help. It's too much like drowning.
Darth Vader is saying something, but she doesn't know what it is.
She turns off her waterfalls. They're loud, and she doesn't want to be loud, she wants to be quiet, and still, and not wasting air, and trying to make her heartbeat go down. It's too high. She's not gonna make it long enough if she can't slow it down.
(She hates herself. She hates herself more than she's ever hated anyone. Exponentially more. She's useless and pathetic and immature and full of awful dark knotted ugly feelings, and she wouldn't be in this position if she hadn't been ridiculously, stupidly prideful, but she was, and she has to be humiliated about it now and if she's very lucky that'll be all it is, and she won't die and go to hell, it's just that everyone she cares about will be disgusted with her.)
I can't breathe, she says, even though this is stupid and obvious.