It's unfortunate, Anna and I'm sorry it hurts when trials like this seem to be like a "Polar-Express," ramping off into some sort of parallel Universe.
When, there's an issue from another person, placing blame outside of themselves onto a partner, roommate, friend, even relative, almost always, the problem lies w/in them and NOT you! That's the first thing.
Secondly, depending on what the issue that lies beneath really is, sometimes, this is a route that's taken to purge a release of frustration of some sort, like they're failing in some manner and choose to project it onto someone else...like "You made me...." whatever.
Or, could be the fights are a way of building up an over complex to act in a way they could not if they weren't mad enough to do so, such as leaving or cheating...it's like a diversion, sort of.
It gives an excuse or justify doing something.
Either way, relationships are hard and if you've one that's constantly pointing blame, that can even turn into emotional abuse, which in effect can be made even worse when the person appears appologetic (meaning you).
It can sometimes be they want you to get made back so they can act....justify a means