Depending on who you're submitting your grievance to, they might have a word limit. When I filed my grievance with the board of psychology in my state, I wrote 4 pages, had it reviewed and revised several times. I went to send it... nope! Character limit. So I had to delete like 2/3 of my letter. However, I was allowed to attach files too, so I attached my original letter. Most of what I sent were emails. I submitted all of them and highlighted parts of interest. I used those parts as evidence in my letter.

Something I realized afterwards: less is more. I should have kept it concise and not send irrelevant emails. My sister went to court and discovered the same thing. So stick to the evidence and try to save your feelings for a separate part/paragraph.

That's my 2 cents anyways.