Op, I spent many, many years in love with my best friend. I do not know what opportunities I missed - I never saw them as I was too busy looking at him. In the end, I wanted to die, too.
You went through hell to get an apartment for all of you. That's very noble of you. You are making this sacrifice to prove your love, to show her that you are worthy of her like some fairy tale Prince and you will get the reward of true love.
Instead, you are Cinderella, slaving away for no reward. She will not run into your arms for a happily ever after. This is normal service as far as she's concerned.
You say that they will both be in a position to pay their way soon. This will tell you what you need to know. I reckon that neither of them will start paying. That's your job.
I know about the crying and pain. It does not get better. It gets worse. I realised that I was just protecting myself from other relationships. Protecting myself from being hurt, ironically by inflicting excruciating pain on myself. It took falling in love with someone else to make me see how foolish I had been.
What are you saving yourself from?
There are no glass slippers and pumpkin coaches, just more shit.