I think you said it yourself early on……you want to try but she loves someone else and doesn’t want to try and love you.
As hard, and painful, as this is, it is the root of why it should end cleanly now. Anything you put in to sorting this out, and it’ll be a lot, will be stripped from you as it’ll be a one sided effort. I wouldn’t wish that feeling on anyone.
My parents divorced when I was young, maybe 4. My siblings were 2 and another a few months. Growing up with 2 happy individuals in my life, as opposed to an arguing, untrusting, couple, has done me zero harm and has left me with much fonder memories of childhood than some of my friends whose parents went the other way.
It’s hard, will make you feel sick I’d imagine, but in my opinion (for what that is worth) you should ask her to politly find another place to stay whilst you both begin to seperate. There is no reason you should be the one to leave by the way – my dad raised us.