I have to admit that ones one thing that I ahve been very lucky with and thats the fact that my Cats generally get along well.
Miquelito and Tubster Panther have "fights" but its generally in a big brotherly sort of way as Tubster Panther never hurts the smaller Cat at all.
I wish I knew what to say, but they may have to be seperated if there that much ill will between them.
We certainly hope that you find a solution that you all can live with, our prayers are with you.