[It's perhaps less him holding her up than it is both of them keeping each other from collapsing on the ground, though Bucky can see it's different for her (of course it is, this is why she wasn't sure she wanted the feelings back at all, and knowing even a fraction of them is enough to make him think in the same situation, he might have wavered, too), that whereas for him it's fading by the second, the panic and pain and the urge to keep fighting... for her, it's not.]
Hey, hey, it's- you don't got anything to be sorry for. Not you. Not ever, okay? [Now that he feels less like his lungs are going to give out, he breathes, slowly, wrapping his arms around her, just holding on.]