Take the following two messages into consideration, the first written by me, the other a response from its intended recipient.

Email #1, from Cameron:

Sonja,
This is one of the hardest messages I have ever sat down to write.
After giving it thought, I think it's for the best that we do not have any more correspondence.

Let me say up front that on the occasions where you have been able to reach out, you have been a tremendous friend.
You have given me advice I will forever cherish, advice that has helped me turn my life around and become a better man.
However, I realized that things were happening on your terms, and that the enthusiasm I had for you went by and large unreciprocated.
I wanted you to be my teacher...and now I see I have taught myself more than you could ever teach me.

Maybe it's not fair to put blame on you, if your schedule is indeed as hectic as you have claimed.
But I feel like I have prioritized someone who only ever saw me as an option.
It is painful and frustrating to be 'managed' in such a way...and while I'm not the smartest person in the world, I am smart enough to know when I am being pushed to the side...to know that I deserve better.

There were so many times where I came to you seeking knowledge, or even just to ask you how you've been, only to be met with radio silence.
At one point, almost two months went by where I never heard back from you.
If the roles were reversed, I would have never done that to you.

I am not in awe of you or your accomplishments.
The way we treat others counts for more than the way we make a living.
The one good thing about being ignored the way I was is that it has helped me to take you off the pedestal I had you on, to see that you are just a human being.

One day, when your career is at its end, and you are looking back on all you did, I hope you will think of that young man from South Florida who saw so much more in you than you may have seen in yourself.
I hope you will think of those who came to you the same way I did, and ask yourself if you did enough for them.

Believe it or not, you were one of my heroes, someone I idolized and modeled my style of acting after.
Now I know I have to be my own hero, and find my own style.
It won't be easy, but with hard work I will get to where I am meant to be...and if I have to do it without your help, it is a challenge I will gladly take on.
Win or lose, I have to keep moving forward.

I wish you nothing but the best.
Thank you for everything you did for me.

Warm regards,

Cameron McCaffrey
cmccaff1@fau.edu

Email #2, from Sonja:

Well, I can’t say I blame you…..I have been hugely occupied, lost my horse buddy of 30 years, and haven’t felt much like getting chummy with folks. When I have been in touch I have tried with all sincerity to offer the best of my own personal life experience. 
Sorry I couldn’t always be there for you.
Wishing you the very best,
Sonja

Is there any realistic road back to restoring the friendship?
What would be some good ideas for an apology letter, or at least something to end everything a little more amicably (bearing in mind that I may not have been in the best mood when I wrote the original message, or taking the recipient's feelings into consideration)?
For example, I already knew of the horse (an Arab named Khalil) passing away, and had even offered words of comfort following the loss.
If you could draft a letter to make amends, what would you write?
Thank you very much for your help