Congrats on taking responsibility for your feelings and actions But, I felt the same as Astrid and Traveller about your second paragraph. I think sending the email as it is would push her further away. TBH, it feels like there's still passive aggression hidden in there which I think you need to weed out. Maybe you can start by thinking about what is the objective of your second paragraph is? If it's to convince her to commit more time to the friendship, then I don't think the words or the tone you've used will help achieve that.
Same as everyone else, I would rethink the second paragraph.

But I think it's great that you are prepared to address this.
FWIW I understand how you feel about speaking to her in person, but I just wanted to let you know that (for me, anyway) it definitely gets easier each time you do it. And the feeling you get once everything's out inthe open & you know you've done the right thing is awesome
So maybe start with a letter, but keep it simple & use it as a starting point to talking in person - that way you can go into more detail if you need but you're interacting with eachother, it makes some of the more sensitive stuff a bit easier to get out KWIM?

Good luck