She could get royally screwed if you decided to pursue that, which you should.

OP, where do you work? Most employers have a fraternization policy that prohibits co-workers, esp subordinates and managers from having relationships outside work to prevent this very thing from happening. Don't mix business with pleasure.

to #46 Maybe a better suggestion would have been sexual harassment complaint, filed with HR or the labor department. If OP were a long term employee, and even with only 4 years with the company OP has some seniority built up with this company, like extra vacation time, pay raises, retirement benefits, possible even profit sharing that he is losing when he leaves this company. And he probably will not start off at the same pay grade in a new job as opposed to 4+ years with one company. Getting a new job will not replace these so, yes, I fill that OP is due some compensation for these loses that will only be recovered with legal action.

She was obviously disappointed with your performance.

She cannot fire you without a reason, you show talk to someone about it, with the right knowledge you can terminate her employment

Did she actually give a reason for firing you? Cause if not you could probably seek charges or somehow get your job back.

YDI for dating your boss. That's a little unprofessional in my opinion.

lawsuit

You're gonna make a whole bunch of money when you sue.

This is where HR or an attorney comes in handy