The police have been involved, but nothing done to remove the Ex.

she also mentioned that she has called the police before when outbursts and abuse has occurred, but it takes 8 hours for them to come, and they have openly told her there is nothing they can do based on their same sex relationship. 

I’m sure it’s a rare occurrence, but I do not want a STR in a location where a guest can have the police kick me out of my own house.

She's a former police officer with three kids.

Roommate A may want to consider reporting this to the police.

Just when you go to change the locks and what not make sure you have your court documents handy incase the police show up.  

@Sterling WhiteI do not, I am speaking strictly from criminal statistics, and close friends who are police officers in some of those neighbors and some of the issues they deal with.

Call the police, ask them to speak with your neighbor.

The crime tends to be concentrated in a few areas (probably best to avoid those), but has decreased in others (like the area near Spring Lake, now that they have a police department).

That is where a police officer will avoid getting into contract law while standing in the doorway.