I understand your pain. I'm the only writer in a small shop, we have four "art directors" who are in reality, glorified designers. My CD knows this, and there's nothing we can do about it, so he has started teaching me how to handle them and ensure that my ideas are carried out the way I want them and that I don't just brush off as the designers as useless asshats.

It's hard to do, as I'm more of a blunt object than a supportive optimist, but I would suggest just trying not to let it anger you or create a void, especially one that could reflect negatively on you to your CD - not just from the work you are doing but the way you handled the situation.

Try to stay positive, and remember everyone has value. He wouldn't be there otherwise, despite how terrible you think he is. Find out what his strengths are and try to find ways to use them to your advantage to get the work you want.