Background check is pretty intensive. They want you to give them your work history and they want to contact your previous supervisor. We interviewed this pharmacist and offered her a position. During the background check, her previous supervisor didn't have nice things to say about her. Did we know it was true or not? Of course not but that didn't matter because we had a line of pharmacists applying for the position. We withdrew the offer and that was the end of it.
So what options do you have?
A) If you lied about it, then you are going to get caught.
B) If you are straight forward about it, then they may not give you a chance.
Given these two options, I would rather go with B. At least with B, you still have a shot. In addition, I would send a letter to your previous HR department informing them that they are liable if they say negative things about you, assuming you didn't do anything wrong of course.
But who knows what you did. Sometimes, HR has a legal duty to warn other employers. They may even have a legal duty to report what you did to the board of pharmacy. It sounds like you are looking for a loophole. If you had an abusive boss, then I feel truly sorry for you. But if you screwed up, then this is the consequence of your action.