Instead of blaming yourself, understand that they mistreated you and that you're not responsible for their behavior. [substeps] The point to bear in mind is that a psychopath typically seems friendly and personable at first.
[header] How to protect yourself from a psychopath [title] Call emergency services if you're in immediate danger. [step] Psychopaths are experts at manipulation, deception, and shifting the blame away from themselves. Your situation doesn't have anything to do with you being naive or an easy target.