Company following up on threats

I was a supervisor and passed over for promotion to production supervisor, even though I was handling the duties when the regular supervisor was absent. I was called into a meeting by senior management and was accused of racial harassment and not allowed to respond to the allegations. As I felt I had a target on my back as the project faltered, I felt harassed myself, I requested a LAYOFF by email with HR. She asked me to reconsider. I did and she had ran to management. She said that mgmt ACCEPTED my resignation and I MUST change my request to resigned. I did, but put the part about being accused of racial harassment without due process. HR said that I would "ruin" my reputation in the industry, if I left it in. I found part time employment in a different field, six weeks on the job, people that I never met are slandering me that could only have come from the job that I left. Any suggestions? I feel that they are following up with the "ruined reputation" threat.