Sounds like it needed managed earlier. It's always difficult to see that in the moment, because ultimately you want to make music, not manage drama.
Since it's already gone this far I'd say a sit-down is needed. Not at rehearsal, not at a bar over drinks. Make it clear it is a business discussion. Be clear and blunt about expectations.
For me? Lash out on stage in front of an audience? If it were Etta James herself I'd end the set early, get backstage, and fire her then and there.
As for her working at the booking agency or whatever - that's difficult. Does she have sway through badmouthing you? Maybe, you can't really know. It's just as likely they know who she is and will assume you made the smart move. Again, don't know.
Hoping you get back to more music less drama soon!