It is not only people in prison or people in abusive relationships that use that word. It is a commonly used word among American youth, It is often used in a comical way (see "I'm Rick James, bitch!), it is often used in an affectionate way between friends, and it is often used in a harmful way.
Your personal tragedy does not give you ownership of the word. It does not give you the right to dictate the way that society uses that word. People will continue to refer to their friends, enemies and victims as their bitch no matter what you or I think of it.
Actually, I was much more offended by his comparing his situation to that of a battered wife, thereby demonstrating his total lack of understanding of what spousal abuse actually entails.
In any case, I understand that I'm unlikely to persuade him to change his use of the language, just as this thread has clearly failed to persuade him to change his approach to conflict. *shrug* The struggle is still worth the minimal effort it took to post.