Lorraine,I'm sorry to hear this. This kind of reminds me of Storm's and Cirrus's battles but they happened almost every day. My other cats were also afraid of the fights and then Storm's health became affected so I had to rehome Cirrus.

I think that you need to talk to your son about Sades and keep him confined in your sons room for now. Will your son be living with you much longer? If not then this will be a good solution until your son moves out. How attached is your son to Sades? Would he ever consider rehoming him? These are things that you need to think about. I hope that everything will work out for the best. Please continue to keep us updated.