But at least you're starting to see this for what it is... really bloody difficult! Thinking of what words, how to try to get your feelings across. Unbelievably hard.
You're already taking pause for reflection. Good on you! Personally, I think what ever we write, it's not going to be fully heard. Not at first anyway. The shock, grief, anger etc will all get in the way.
Something stopped you. I can only speak for me, I get that. The amount of times I started a letter, broke down, deleted it, started again... geez!!
Breathe! Reflect as you are doing. Be gentle on yourself.