Wow! I can totally relate! I have gone through this twice this year. I generally give families 4 weeks in order for behaviour to change. I make sure to keep the parents informed (and not sugar-coat) the behaviour of the day. That way it isn't a surprise when they receive their 'letter of dismissal'. When all else fails, and the tatrum begins, I will go as far as to put the little one in their room in their crib and re-enter only when their crying has ended and try to re-introduce them to the group. If I find myself on the verge of tears everyday because of extreme behaviour, I feel I have no choice but to terminate...for both myself and the other children. Good luck!