Hey Benjo!
I dont know whether you wrote this with a specific woman in mind, but I can give you a personal perspective on it, as someone who has a tragically deep well of experience of not being able to move on!
So...all from my personal pov.... I think for me "in my head I'm the one to blame" is too simplistic, too black and white.... In my experience, I'll spend unbelievable amounts of time agonising over who is/was to blame and running through the whole gamut of emotions of wild anger towards the ex, introverted anger, self pity, self doubt, frustration, a sense of inevitability, feeling of having senselessly lost something, and of being lost.... Obviously you can't put all those emotions into one line, but i think if it were me, i would be making that line into a questioning line to hint at the internalised struggle of trying and failing to make sense of something.
I really recognise the line about "the least you can do..." etc... I think there's a real sense of "you owe it to me to make me feel better by making me understand (and if you won't/can't do that then I'm gonna make you feel as bad as i do by making sure you have to confront what you've done to me)"...
I also recognise the bit about taking away what she treasured....and add to that a sense of disbelief that he didn't also treasure it like she did....
I think the line about "no matter what i say or do, you won't understand the way it feels".....to me, that sounds like the mind of someone who is resigned to a situation.... But the mind of a person who can't let go is more likely to be thinking, "i
will make you understand how this feels"... somehow someday...
I didn't really understand the line about pushing the chair away..... But then just reading it again it came at me with a bit of a jolt...... Do you mean she's hanging herself??..... If so....wowsers! No prisoners hey?! That's bleak!!
I really really like what you've done with this. The things i mentioned above are obviously a personal take on it that could help to make it ring even more true to me... However another mad crazy lady's perspective could, of course, be completely different again...
Btw I'm not really crazy!!! I just have my moments!