Levi,
When I was 23 I wrote a letter to my father because I felt like I was never able to tell him in person how I felt. Usually because he was intoxicated or just wouldn't listen. I wrote a long letter telling him how things felt from my perspective and how much he had hurt me. I had a little bit of hope that the letter might open his eyes, but tried not to expect anything. Just writing all of my thoughts down was actually the most therapeutic part of it anyway.
He recieved it, sent me a greeting card back that said, "Something went wrong and I think it was me." with Garfield on it. I was excited at first until I read the inside and it said, "I got your letter, but am not going to write one back because letters are a one way conversation. You have the wrong idea about a lot of things and we need to talk."
I never talked to him about it again because it was obvious nothing I said in the letter sank in. To me there was no if's and's or but's about his disease and I didn't care what he was going to say in his defense, I didn't want to hear it. I am still glad to this day that I wrote it though. I know he loves me, but he will never "get it."
I have friends who have written letters to relatives that are deceased, and they say it is very healing. Writing gives you a chance to purge a lot of emotion out of yourself. You can start the healing process and stop carrying the weight of it all on your shoulders.
I will also say that from my experience, I think writing a letter to an alcoholic parent takes courage. Whether they let it sink in or not. I felt better about myself after I did it. The rest of my family members preferred to act like his disease didn't exist, and I was facing it head on. I felt strong. I wasn't keeping my head in the sand anymore, I was putting it out on paper.
Those are just my thoughts, hope this helps!
Gemini