I want to thank everyone for their input. Here are my thoughts, based on your feedback...
1) It woud be OK to use the B word in the proper context (i.e., from the villain's mouth).
2) The word might seem too cliche. I remember reading an historical novel that used the word Fuck before it was even a word. That cheapened my impression of the writer and their work. It seemed lazy. More than anything else, this gives me pause in using "bitch". Even though it would be historically current, it may not strike the reader as being realistic for the era. And really, what reader is then going to research it to see whether it was in fact in then-current use. They might just think I was lazy.
3) There are alternatives, though none seem as true to the feelings/resentment with which the word is delivered.
4) Making up a suitable alternative is difficult.
5) My current five best alternatives, on which I welcome your feedback:
i. Witch (For context, the villain is convinced my protagonist slept with her commander to obtain the role of captain. In other words, she bewitched him. So it fits in that sense.)
ii. Wanker (A contemptible person. Problem - it lacks an anti-female element. Yet it contains within it a male connotation that might be fitting, given my female protaganist initially presents as male)
iii. Drek (Trash. Short, to-the-point, 4-letter word. But again, lacking a specific anti-female element)
iv. Vrack (Totally fictitious)