While its likely little comfort, I've generally found that those using animals for religious rituals generally treat them better than even most owners. The whole "point" of sacrifice is that you are giving up something of value to you - if its not valued to you, its not a valuable sacrifice - that's the law of proportionality, and it holds true in virtually all magical traditions. The process of dispatching the creature likewise; most typically its somber, respectful, and swift - again, as good or better than the typical backyard owner who doesn't routinely process their own birds.
I don't personally practice such beliefs, but I have studied many of them, in print, in video, in person, and as an assisting participant.
There are worse ends.
At the end of the day, you entrusted those lives in your care to another's, and you chose poorly. Your legal recourses in the absences of a clear written contract, however, are unlikely to result in your victory, much less your satisfaction. So are hers against you, regarding any opinion you post online regarding your experiences with her.