Hi Paul...I have two lovely male Rotties who absolutely despise each other and will never get along. We have to keep them seperate at all times - we do have plenty of room, and crates & seperate yards & all the rest - but it is still difficult! Like you, we very much like our dogs to be part of the family...it is stressful living with these two.
If you do a search on fights/fighting on these forums, you will find quite a bit of discussion...there are several people who post here in the same situation. It's probably unlikely you will ever get yours to live in harmony.
I'm with Judi here - do what you can to find her a suitable home, if at all possible...bless you for rescuing her - good luck with the situation!
Feel free to PM me if you want...I must get back to my taxes now
but I know just what you're dealing with. A crate is still a good idea, and also have a back-up plan for breaking up fights so you won't be unprepared the next time...