People suffer worse diseases like cancer, spend lots of money on chemotherapy and most times, die even after all the money spent. One of my colleagues died of cancer, aged 38, left four kids. Now which woman will marry a man with 4 little kids?
Have you see people that suffered stroke with the consequent paralysis of one side of the body? They are still people's spouses.
A man I saw in church the other day had one full arm chopped off from the shoulder!
My point? Mental illness is not the worst illness on earth. My inlaw died of prostrate cancer, left 2 little kids. So your brother should thank God that she's still alive. If she's violent, take her to a psychiatric hospital so that they can calm her down with anti-psychotic medications. If she's not violent, call a psychiatric doctor to see her at home and you pay for his home service. Bad luck happens to everyone at one point or the other in life. She will be fine. Also Pray for her. From my experience, most psychiatric illnesses are spiritually induced. Forget what a probably jealous person said about her past.