Basically that is my question, I was going to add into the letter just how I hope for her to have a good life, and the best of luck with who ever she decides to be with. That I understand she is dating another man and seems to be very happy with, which I am happy for her to have found a new man. That I know I should have been a better man then what I was, and should have done certain things different, but that won't change the present situation. That I know I should have shown my passion better, through telling her how I truly felt and acting differently. That is what I have written basically, I don't look to get her back, but I look to allow myself closure knowing that I truly have done everything that I could have within my powers to have told her how I truly feel.
Most Helpful Girl
I think if you only want closure from this then send it, but be warned that if you didn't break up amicably then its likely that she won't view the letter positively.
If you want to get her back, or even maybe just get a reply then I'd say don't send it.
However, if you DO send the letter, try and keep it light, polite and friendly. Don't put recriminations in there and don't rehash the past any more than to just say that you enjoyed it while it lasted and that you wish her all the best.0