There's no JW anything that forces her to not have a male roommate.
A jw woman absolutely cannot share a flat or house with an unrelated male, jw or not.
However, this is not the case in this instance. There are seperate entrances (presumably it's a house conversion) which is absolutely fine as they are physically two separate properties.
You didn't mention if she or her relatives are your landlords but I presume they are or this wouldn't be an issue. If they are I would recommend taking legal action and although they can make you leave in the end, of course, you should receive some financial compensation.
It might be worth mentioning this to her/relatives/landlord as perhaps you can come to some arrangement whereby they recompense you financially for moving without having to go to court