When he said you ruined his life, I think he means you ruined his set up (which of course you didn’t, he had set himself up to be doomed), and if he loved his fiancé why would he need you too. Perhaps he needs to leave and join a polygamist culture where they can all pretend to love each other equally on tap, whereas you will be free to find the exclusive partner you deserve.
It seems like she is having some sort of depressive episode, but if she doesn't admit or acknowledge it, there isn't much you can do because she won't admit to needing help. You can reach out again in October after no contact, but I suggest taking it a step at a time to see how she responds to you, and whether she still seems to be depressed at that stage.
This is great Eric. I’ve struggled for a while with a guy that’s not really been putting in much effort, I think because I was always there waiting for him and over functioning. He’s just broken up with me and I realise how much of myself I had lost and how I wasn’t taking care of my own happiness. I kind of for drawn into his hot/cold behaviour and felt anxious uneasy. I’m going to take my life back and take care of myself and be gracious and honest with him. I shouldn’t pin all my hopes on another person but all my hopes on myself. I really hope for a big shift on perspective on the inside after this. Of course I am heartbroken but I realise I fall into the same pattern in every relationship so this breakup is a big sign to change.