Dear Damon,
I'm writing this letter to let you know that I've decided to return to my hometown. I know it may come as a surprise, but I cannot face you even though you said it was fine. I don't see things going back to normal between us.
My illness is starting to hit me harder, and I feel it's best for me to be back home during this time. I apologize for not telling you before leaving, but I didn't know how to face you and explain my situation.
I want to thank you for your kindness and understanding throughout the competition. You've been a good friend, and I wish you all the best in your future endeavors. I hope that we can remain in contact and, if I make it through this difficult time, perhaps we can meet again in the future.
Once again, I'm sorry for leaving so abruptly, but I believe it's the right decision for me. I wish you success and happiness in your life, and I'll always cherish the memories we made during the competition.
Take care,