I think you’re so entirely focused and consumed by her that you’ve forgotten you are important too. I have been in a similar situation where I put my partner before me, it didn’t end well. I learnt that sometimes, no matter how much you love someone, they may not be ready to reciprocate the same kind of energy and that is okay because not everyone is meant to stay. We learn and we focus on being better individuals for ourselves. I suggest you take some time off these toxic situations, and just decide, is this how you plan to see yourself in the future?
Do not self sabotage by blaming yourself for her behaviour.