Besides your director clearly not having any professional man-management skills, it�s obvious he�s a bit of a jerk!
Actually I feel you�ve answered your own question here. You are not valued, nor does it appear that you are going to be.
Now, if I look at it from another perspective: Could it be that the director is weighed down with declining profits, slim margins and possible over-staffing situations. Facing the possibility of redundancies, he may be of the mind that if he simply irritates someone, they�ll just leave, ergo making you the object of his affection (as it were), ergo doing what he might not have the professionalism or skill sets to do � to be honest and forthright and make staff redundant.
And saddest of all, his behaviour now suggests that he has made you his target of ridicule by so flippantly writing a response in such a way.
I would encourage you not to do anything rash. Instead, methodically, and deftly seek a new position.
When you serve your notice do not demean yourself or your own professionalism by stooping to his level. Make your resignation letter polite, civil, and professional, thanking the company for the growth �and personal insight� you�ve gained by working with the organisation.
And then get out with dignity and a sense of relief!
I wish you every success
Fr Bill