I didn't notice that this thread was from almost 4 years ago, but I have to say the letter touched my heart and I think it was a lovely letter...a letter that allowed the OP to express her feelings and how addiction had brought her to recovery, and I think it also validated her "letting go". It was not unkind or shaming, it was honest and loving and I think that makes all the difference.
My prayers go out today for that mama and her son, wherever they are, however they are.
Hugs