Love the idea of writing a letter.
My friends daughter had a very traumatic childhood, and she told me that she found a way every night to help her sleep, by envisioning a hot air balloon tied down with four ropes, and ever so methodically she loads up boxes with all of the stresses or pain she is worried about at that particular time, and then she loads them all into the hot air balloon, and then she picks up an axe, and goes round all four of the tethered ropes, and cuts into them one by one, until the balloon starts to float away. She watches it disappearing into the distance, and watches it until its completely gone, and then finds shes asleep.
I started doing this with my worries and problems, loading the balloon, and now I fall asleep before I have even cut the ropes lol.