Completely disagree with all the advice saying to ring the NHS helpline because the moment you mention chest symptoms they will probably recommend a&e "just to be safe" because they don't want to be sued!
OP you keep saying you know now she's not likely to be harmed but then coming back and asking more and more minor questions about if the vape could possible have hurt her due to x, y, z which probably isn't helping if she's taking that as you humouring her delusions
literally there is no possible way, battery in battery out, light on light off, tank full tank empty, picked up off the ground with possible soil contamination.....
that someone taking a few puffs of a vape will harm them. Honestly. Whatever she says just keep reiterating that. They are designed to be safe and pleasant to use, why would the makers design them to be dangerous once they'd been emptied???
A few puffs on an empty vape is as disgusting but much less dangerous than a few drags from the end of a fag. Honestly the biggest danger is putting something in her mouth there's a highish chance a dog has pissed on (obviously don't mention that to her!). If her chest is hurting its probably because she's been screaming and crying for hours!
I'm sorry dh has added to your stress and you honestly sound like you are coping amazingly with it by the way, must be horrible for you to see her so upset and probably know you want to leave yourself to get away from it but staying there for her.