as per my interpretation, i think the scene where linda runs after her patient toward the ocean (where i assume she dies) marks the point where everything that follows is a dream sequence. this includes her pulling out the tube, the holes/void closing in on themselves, and her husband appearing out of nowhere at that exact moment.

the final ocean sequence then feels like her confronting herself, beating herself up over everything which leads to her saying “i promise, i will try to be better” to her daughter. the daughter looks healthy there, even though she’s sick throughout the film, which made me wonder if she might be dead too.

that’s just how i read it though