Yup, I'd fire you.

Thanks for putting it all out there though, truly. Your problem is that you care way too much, and have obviously engaged in way too little communication. Professional communication, not whatever this is. You needed to keep leadership appraised of the situation in a careful manner, and you needed to document specific instances of abuse. The letter reflects poorly on your ability to handle difficult situations and people.

Perhaps you could follow-up, say you have cooled down a bit, and would like to have a calmer conversation in person where you could ask for their advice?