Well living with somebody and leaving all the shitty work for them to do, when it is meant to be a cooperative effort is, indeed, behaving as a horses arse. Doesn't mean I hate her. But her behavior is not an admirable one in this particular case. So with respect to that, i stand by my words.
Leaving it all for you to do, is lazy on her part, and its taking the piss out of you. She needs to step up and do her share, not leave her crap for you to pick up. Why should you be expected to do all the work, and another benefit from it whilst making a habit of not contributing back? That to me, does not mean a fair, equal partnership.