Gosh, I feel so intimidated sometimes by persons who seek to verbally bully me. What can I do to deflect their assaults?

Setting aside more violent possibilities, you can read The Gentle Art of Verbal Self Defense by Suzette Haden Elgin. It’s been years since I looked at it but I recall that Elgin offers some sound insight about what’s going on in these assaults and techniques to defuse them. She has also published several sequels on the subject.

Probably the most important thing is simply to abstain from discussions in which the other person isn’t going to be at least as semi-reasonable as you are. Have the presence of mind to suggest that the matter be addressed when emotions have cooled a bit. Decline to get dragged into a combat you can’t win. That’s often easier said than done, of course. The whole point of verbal intimidation is to throw you off kilter so that you don’t have the presence of mind to defend yourself properly. But if you’re conscious of what’s happening, that’s half the battle. Even dead silence is often better than being lured into a position where the other guy can just stomp on you at random. If you’re not an unprincipled screaming manipulator and other guy is a veteran unprincipled screaming manipulator, he’s just going to be a lot better at hitting below the belt than you. And more willing to do it than you. So don’t play.

Jay Morrisay offers some thoughts at his self-help site.