She takes and takes and doesn't give anything. Nothing is ever her fault and there is always a justification for her actions. I am constantly wondering if she even thinks of me or realizes what she's doing.
that does not sound healthy or balanced in the slightest. i read some of your backstory, this is a woman who has cheated on you MANY times, has a whole host of other transgressions, and you've only been together about 3.5 years.
her issues aside for the moment, let's focus on you. what DO you get out of staying and fighting? why do you take the abuse and disrespect? what are your dealbreakers? have you gotten so accustomed to the "battle" that you forgot what the point was?