Just plow through it head on. I'm exactly where you are. Maybe we're suckers for punishment, but I too have purposely found jobs where communication is important. I used to work as a journalist; imagine an important press conference, with TV crews, important delegates, and I'm standing there, all eyes on me... and I just c-c-c-c-c-can't get the question out. But you know what, I had others come up to me afterwards and say thanks for asking those questions they hadn't thought of! What you have to say, how you make people feel, a smile, they all have a lot of value in communicating. And remember, your moment of disfluency sticks in your head far longer than in other people's. Before, a block or two used to haunt me for hours, but now I try to get over it as soon as possible. Dwelling on it just leads to more anticipatory anxiety. I am finding that meditation helps me to stop ruminating on such thoughts. Best of luck and stick in there!