Most Helpful Girl
In that entire speech, you did not explain WHY you love this girl and want to marry her.
This entire thing was about how bad you feel, how you got yourself into a bind, and how she's paranoid. These are all good things to mention, but because you don't have any reason to explain why you love this girl so much, it makes me think that you only "love" her out of convenience.
Why did you think you were not the guy she was supposed to end up with? What made you change your mind about this point? (NOTE: Your whole experience with the rich chick really did not affect this issue, so what changed your mind?)
You completely bulldozed this girl's heart repeatedly for an extended period of time. She will never be the same. Your relationship will never go back to what it was. It's possible you'll both be able to grow beyond it and move past this whole thing, but it will take a lot of time and a reestablishment of trust. Even then, she will have a scar from this whole thing.
You are not ready to marry her. She is definitely not ready to marry you - she isn't really even ready to date you again it sounds like! You need to sit down with her and ask her to tell you everything she's feeling. Say as little as possible. Just let her get all her feelings out into the open, and you can move on from there.