This may sound silly, but I've written several and torn them up.
This is a tremendous catharsis. I have written so many of these letters it isn't funny. I know some people who have made little altars and actually burned the letters. They got great release from that. Apply the 48 hour rule to these letters. If you feel incensed, write your letter, but wait 48 hours before doing anything with it. Chances are, you'll feel differently. The WORST thing you can do is get p*ssed off, write a letter and send it off immediately. You will always feel sorry for doing this.
Same with phone calls.
Do this with the love letters, too. You may have these feelings as well, but the time may not be right to reveal them. MLCers aren't too happy with ILY while in the tunnel. They run faster.
I waited 6 months with a letter before I sent it. I would review it every so often and change the wording, because I realized I had grown and I no longer wanted to phrase a particular thought in a certain way. When I was ready, I ran it past some people on the board who are better at this DBing stuff than I am. One more rule of thumb: if you DO write this sort of letter, expect NOTHING in return. My biggest mistake was writing an apology letter and sending it with an expected outcome. I don't know how far I set myself back by doing that.
David
The fires of true love can never be quenched, because the source of its flame is God Himself! - Shulamith