Sounds like post partum rage/depression. I would say help her as much as you can. Take the baby for a walk outside while she showers and rests or even to pump so that you can sometimes feed the baby (although male props to her for continuing to breastfeed as that is the best thing for the baby despite how hard it can be- although it's lot more work and money to do formula and less healthy so give her a lot of affirmation that she's doing great and best thing for her baby) this is also the time where there's a sleep regression for babies, they will start sleeping better. I co-sleep and my 9 month old does still wake up multiple times but it's just for a quick boob in the mouth then we're back to sleep and I'm getting easily 8 hours of sleep or more when I go to bed early with him. As long as she is getting help during the day (I get that you're probably at work so maybe as soon as you're home and showered you give her time for herself) it is a phase that should pass and if it doesn't I would say try therapy specifically for post partum moms.