do I sue the company for coerced resignation, deceptive boss, unfair treatment ? And threat to be fired if I explited the affair.???

10 year employed in a anesthesa group. I had relationship with president of company and boss for years.. last year tried to stop relationship . he came back ,bought me stuff, dinners, lunches, had sexual relations. his wife found out and demanded I get fired. he has sent me fake termination letters to threaten me since last nov. when I retailiated he would start the relationship up again and butter up to me and I believed everything he said about how he felt about me. He said his wife she wants me fired. For a year i feared for my job not knowing when I would received another termination letter . They were never sent to other partners it was just to me so I would resign on my own. This went on till july 30th off and on. another termination letter to me dated for sept 1 I panicked, felt trapped pressured and sent back to him resignation letter for sept. 1. He continued relationship the out of blue 2 weeks later resent my resign letter to the company without my knowledge or permissi