Good letter but I agree with NNP, don't give it to him! You know that I am divorced, I wrote my H a letter & gave it to him. I didn't ask him to come back to me, I did tell him if he would stop his R with OW & us get C that our M could be better than ever. I also told him in the letter that with much regret I was letting him go. I had to let my lawyer read that letter. He wanted to make sure that I didn't put anything in there blaming myself for the break up. So, if it gets legal in your sitch (I hope it doesn't), but you will only be hurting yourself legally.
I think it was good for you to write the letter for you but I wouldn't give it to him.