I feel for you! I have a dcg that I am having issues with. Her issues are actually very much the same as your dcb and I have considered terminating care. May I ask how long you dealt with his behaviour before deciding to terminate? She has been in my care for 2 months but this behaviour has only been about a month and I don't know how long is fair to wait and see if it will stop
I would keep the letter short, professional and to the point. Like others have said, keep emotion out of it. Good luck!!!