Even if it IS just in your head or physically it doesn't matter because, regardless to how it's happening YOU still feel the pain. Sometimes saying less to the bully is better. I like to kill people with kindness, if I am able to unfreeze myself when something happens... (rarely)

I liked the ideas @mc2ed talked about. Especially about learning the best responses for the situations. That way you can plan what you say to get the upper hand. Or maybe you could say something then just turn and walkaway. It's hard to learn something new because it feels like it takes soooo long! But, in the end, even if you mess up a few times, will be something great or at least better