If you have worked very long, there is a good chance that there was a job in your work history that you did not leave voluntarily. Definitely don't lie when asked any question, but you don't have to tell them everything you know. as time passes, your perspective will evolve. It's important to take responsibility by acknowledging that you needed to learn something. whatever you do, don't assign all the blame to your stupid boss or a jealous coworker who stabbed you in the back.