Need Advice on writing a letter to the Judge

New to this site and to Foster parenting. We provided respite for a baby boy from last February till August. Then he was placed with us as a foster child and remains with us to present. He is now 16 months old. His mother has voluntarily terminated her rights and the father has been incarcerated since before the child's birth. He was convicted after a jury trial last month and receives his sentencing this week sometime. He has refused to terminate his rights voluntarily. The permanency plan is involuntary termination of the father's rights and adoption by us. We have been asked by the FCM to write a letter to the judge at the next hearing at the end of April. We are unsure how to do this. Everything we've read is to stick to the facts and keep all emotion out of the letter. Due to the child's age, there aren't a lot of facts we can give except that, of course, he has bonded with us completely and the father has not been a part of this child's life because of incarceration. Also, how do you keep emotion out of it? We've been with this child since he was 3 1/2 month's old. He has bonded with the only parents he has known. We, of course, have bonded as if he was our own child. Need help, please!