OIN, You are a tolerable alternative and, frankly, the path of least resistance for her. Sometimes staying is more tolerable than others (peace vs. snippyness); sometimes the trade-off is more reasonable than others (let you do the work around the pretty house vs. having to move and handle it all); sometimes it's an annoying pain in the ass but it's still good enough for right now (I treat him like [censored] but he still does stuff for me).
In her mind you are the root of all evil, and nothing you say or do to or for her is going to change her mind. Your relationship, such as it is, will continue to drift up and down along the "relative scale of suckiness" until something radical happens.
Change the circumstances. You've been told how. You don't want to, that's fine, but stop looking for the way to do it that fits in with what you want to do and keeps you in control. Either you're willing to do what works or you're not, but the answer isn't going to change no matter how many times or in how many different ways you ask the question.
