My boss bullied me into resigning. Is this constructive discharge or wrongful termination?

Six weeks ago I made the mistake of going into my boss's office when I was upset about a perceived miscommunication (she always gave the impression that her staff was welcome to do so) and made the even bigger mistake of saying "Maybe I'm not cut out for this job." I resolved the issue on my end and sent an e-mail later that day saying I planned to do better in future and I wanted to improve my performance and relations with others.

A week later, my boss called me in and asked if I was serious about resigning. I said I was very upset that day but that I had NO intention of resigning. She didn't listen to me and said that "We take any talk of resignation seriously." She never threatened me with termination, but she wore me down enough that I ended up writing a resignation letter and signing it. She told me there was no way I could rescind my resignation once it was in writing.

I consulted with a different employment attorney, as well as a workers' comp attorney (I had been injured at work a few months prior); both told me I didn't have a case but to file for unemployment anyway. I also talked to my HR department, and am waiting for an answer from them.

Was she correct that I could not rescind my resignation? If I'm not reinstated, can I get unemployment? Also, if I file a constructive discharge or wrongful termination claim, will it affect me negatively when interviewing for future jobs?