I think that letter is way too wordy, I understand that you had a bad experience but it seems that the gist of your issue is that the flight was cancelled, you weren't told about it in advance, you experienced a delay rebooking, a delay on your new flight, poor communication and you hated the food.

I'd rewrite it and keep it concise. Explain your issues, explain what you think could have been improved and then send it to AC customer service (you can find the email on the website).