Wow, you are not ready to be married.
I can see that she, your fiance, hurt you very bad, I am sorry for that…but if you are still hurt to the point of writing a letter like that to her you are not ready at all for such a commitment.
It sounds like something you’d write to someone upon breaking up, or to your worst enemy..not to your fiance before your wedding day.
The problem here is, these are your true feelings about this woman.
I agree with Josie that it sounds like you want “the love of your life” to feel pain.
Not only would I not give her this letter, I would not marry her..not with feelings like that hidden inside.