Wow, the individual who made her hand look like a gun like that was out of line. No wonder you were severely triggered. Some people who claim to "know" what they are doing are not really qualified to work with "trauma" patients.

What DBT is supposed to help with is to help you develop a "wise mind" that slowly recognizes the emotional "triggers/hurts/challenge" and the "cognitive" part of the mind and becomes more capable of recognizing and acknowledging both and in that maintain a balance. Trauma dramatically affects someone emotionally and that individual gets so emotionally overwhelmed that they get fearful and hypervigilant. DBT is meant to help you recognize your emotional challenges and help you slowly develop a healthier way to acknowledge your emotions, but, develop a wiser way of getting more "control" over them.