I was in the same position a few months ago and also had to terminate. I had the same feelings as you but kept thinking of all the circumstances leading up to the decision to terminate. The last day in particular was hard because the child was very affectionate and was behaving well. I think it's typical to have second thoughts. But since he's been gone , I've noticed the time that is freed up for the other children not to mention stress! Don't be so hard on yourself and have faith in your decision, you probably didn't make it in haste!