Working in an environment with a stressed manager or co-worker is always a challenge.
However, when that stress is based on their personal life, and spills into the work environment, it becomes unprofessional.
All of us get stressed from time to time, but when someone recognises they are stressed, but uses this as a badge to hide behind and doesn't take action then its not okay.
In any workplace, one stressed individual and their heightend aggressive (or passive/aggressive) responses can draw in other people, creating a "stress vortex" and ultimately a highly toxic workplace. In a workplace with a duty of care, this is very much not okay.
The really positive thing is that she has admited she is stressed.
If you can, then approaching your manager directly is probably the best course of action.
As with any confrontation, the simplest approach is often to
- stay calm and measured, and don't lose your temper
- reflect back how the other person feels
- use "however" to invert the situation
- present your point of view
In this case : "I know you are stressed, and you have had a terrible time at home over the last few months. However, I'm starting to find your stress is impacting on me and the others here. We are really struggling without your leadership, and so I really need you to get some help with your stress, and start to get it under control."
I've had to do this several times with co-workers, but only once to a manager. It has worked on each occasion, but I will not pretend it was easy when managing upward.
If you don't want to do this, you need to go to her manager. Its important to highlight the professional impact this is having on you, and your co-workers, as well as the potential for some kind of escalation in the workplace.