Did you offer to meet her in a romantic setting? And that is where she rejected you and told you she has a fience[sic]?

You have this long post describing stuff, then at the end it says 'ps: she loves her fiance'. And halfway you mention that in the stuff you told earlier, she rejected you. I don't see anywhere where you offered her anything and she said 'no'.

If you talk with her for hours, and there is no offer of romance anywhere, you friend-zoned yourself.

As I see it she knows you are infatuated with her. You told her your feelings. You lost most of your bargaining power there.

You also tried to guilt her. You brought up that you think she shouldn't be talking to you as much because of her fiance. Right? What's the point of that? If you think this relationship you are having is wrong, why are you facilitating her? And then blaming her?

You telling her you love her so much and her threatening you to never talk to you again? How mature is all that? Why would you ever tell someone you love her so much when you aren't even in a relationship?

Either way, the way she behaves with you is the way she will behave with other men if you were her BF. At least she isn't cheating on her fiance with you. At least she has principles. But she is kind of wavering.
You can either try to continue with all of this, create more drama, see how principled and mentally strong she is. Or you can tell her you think you had a connection, but you know she isn't available, tell her you would be interested if and only if she were ever available, and back off.