I was in no rush to get married. Just recently got divorced before we met. She is someone that I could have married. It was just too soon to hop into it right away. And then things started to change after the miscarriage.
I mean no offense by this but there are few examples more blatant that yours regarding an ex seeking "breadcrumbs" and being "friendzoned". You could be the poster child. You jumped into a relationship soon after divorce when you actually needed more time to find you and, much like a newborn, you "imprinted" on her. You indicated that it was too early to wed her but not too early to impregnate her?? I find this confusing.
Nonetheless, nothing in your posts suggest that you and she are now anything more than friends. You are helping her out by storing her stuff, having her over for Mother's day, she has even now become comfortable sharing her thoughts about other men with her "friend".
I realize that you have done all of this in the hope that she will return but that is highly unlikely. The moon is approximately 250,000 miles from the Earth. If the Earth represents her not coming back and the moon represents her returning to you and continuing your romantic relationship then your position is roughly 5 feet above the Earth, or approximately eye level, it is time to face it.
As to your letter it is acceptable albeit somewhat needy. However, as long as you make it clear that you do not wish to sustain merely a friendship with her then the objective is met. In all actuality it would not be a bad thing to have a friendship with her IF you could actually do that but you have far too many feelings for her for that to be possible. To attempt to be her friend you would be subjecting yourself to much more pain and anguish especially when she start to have romantic encounters and wants to "share" them with you. So, since you cannot overcome your feelings for her, then best to move on and let her find another friend.