On Thursday, she notified the city that she plans to file a potentially lucrative lawsuit to prevent what happened to her from happening to others.

The political fallout from her detention was another blow to Mayor Bill de Blasio’s image as a champion of the poor. Mr. de Blasio has apologized to Ms. Headley, but he drew harsh criticism from other Democrats for waiting several days before condemning the arrest.

For the city’s police commissioner, James P. O’Neill, who has committed to training officers to recognize unconscious biases and to de-escalate tensions, the incident raised questions about whether that coaching is taking hold among officers.

“They never asked me my name,” Ms. Headley said. “They never said, ‘Hello, who are you?’ They never asked me.”

In the interview, Ms. Headley said she tried to leave the office with her son shortly after the police showed up. The officers had been called because Ms. Headley had a heated argument with a female security guard, who told her she could not sit on the floor.

She picked up her baby and started to leave, but the police said the guard grabbed her arm, and they all tumbled to the floor. Ms. Headley said she tried again to go, but a male police officer told her it was too late. She went into “defense mode,” she said.

“In my head, I told myself they’re not going to let me leave,” she said. “I was so afraid. I was combative with my thoughts.”