Hi there,
Sorry for your suffering.
Not having been there to assess the tone and body language of the person 'messing' with you, I cannot adequately answer you. Normally, though, someone might lean in and have a sparkle in their eye, if they're just joking.
Have you ever thought of doing theatre games such as improv? That might help you...
Also you might want to read The Gentle Art of Verbal Self-Defense.
Are you in therapy?