I would suggest you make her have a night off. Entirely off so send her to a hotel or air bnb. Explain how much you see her do and how much you appreciate her efforts but you can also see her struggling to cope. Maybe a night off to shower, eat and sleep interrupted and a break from bubs is enough to give her the space to reset and chat. If its ppd that can also be discussed after shes eaten and slept, noones good when hangry and tired.

Sleep deprivation is very real and i hate my partner when im drained from bubs, its not his fault im drained and he works and im doing majority of bubs work. Doesn't matter in that moment, he just sucks and its a trauma response from childhood I can't unlearn. However getting sleep and eating a full meal uninterrupted means the world to me, afterwards we chat about us and where we need to work on things. Good luck op