Unsure about my brother's partner

This is my first time posting, so I'm unsure of what to say really. I'll try and explain this the best I can.

My brother's partner has schizophrenia, diagnosed well over 10 years ago. From my understanding, she has been unmedicated for the entire time I've known her, which is 7 years. While this has caused issues in the past, especially during her two pregnancies, it seems to be getting a lot worse at the moment and I'm concerned about the effect this is having on my brother, the children, and herself.

She has been acting paranoid and emotionally unstable. My brother works full time, and comes home to do the shopping, cleaning and cooking. She calls him roughly 15 times a day during his shift, which significantly impacts his ability to work, and when free his work suffers because of the fatigue and worry. They live half an hour away from us, in the middle of nowhere, and have almost no access to outside help (or that we're aware of). She has been looking through my brother's phone constantly throughout their relationship to see if he has been cheating (he hasn't), even going so far as to send messages pretending to be him to try and trap someone into confessing. She believes she has "proof" of his infidelity through this approach, although someone not under her stress and illness would be able to see that what she considers proof actually isn't (I could explain this but it would take some time). At the current moment, she does not take medication and refuses to because she believes she can fight her illness herself, however she is unable to take her daughter to school or son to kindergarden and my brother has been late to his job by over an hour each day for a few weeks. He is going to be fired as soon as he returns to work from self-isolation (we know the manager and this has been told to us). The impact she's having on his life and on the well-being of the kids is frightening. She is unable to properly care for herself or them, and my brother is only so strong to manage it. This is the information I have been given or witnessed; I am sure there is more hidden behind closed doors.

He would hate it if he knew I was writing this, but I think it's hit the point where she needs some serious help. I'm just not sure what to do, or if I can do anything. I would go out and help but I suffer my own illness and do not drive.

Please, is there anything I can do here to try and improve the situation for all involved?