If you go to meet with anyone, I would say try to maintain a positive regard for what you think was good about your job performance and, at the same time, be open to conciliation.

Like - "Is there some aspect of my performance that I could improve to meet the expectations? I would like a chance to work on that." I know that can feel like overly humbling yourself, when you may already feel like you have been bullied. Look at it this way: You lose nothing by being very tactful, and diplomatic with management and HR.

Believe me - I am talking to myself, as much as to you on this thread. I was on a job that I liked and I was doing some darn good work. Well, a supervisor and I came to not care for each other. She called me in and said I had a way of communicating that was not appropriate. She said she wanted to arrange for me to take a class in appropriate, effective communication that the company would pay for. Well, I told her where she could stick that class. The company agreed that this supervisor was a very difficult person, herself, and said they would arrange for us not to work together. That happened, but down the line, I ended up getting fired.

Older and (maybe) wiser, now, I wish I had said, "I will be glad to take any class that might lead to my improvement, and I am grateful that the company should be willing to invest in me."

There was a time when my head would have exploded before I could ever have said anything remotely like that. Now, I understand that jobs are not so easy to come by (as they had been, in better economic times, all over the world) and it may be wise to salvage what you have, if possible, before trying to go elsewhere.

Even if you feel job termination with this employer is inevitable, I would say to be as graceful in your manner, as possible, with whoever you talk to, and try to project that to HR. Let's face it - it's possible that your line supervisor doesn't like you and never will. Could be a personal thing (like I've experienced.) Present yourself in a good light to whomever else you can. Avoid sounding defensive. That's what they expect, and it does absolutely no good. Often, it's good to have a witness to conversations/exchanges. When you are alone with someone, they can say you said anything. If you have to leave, try to arrange it so you get a handshake from at least one person on your way out the door. That is self-empowering.

Sorry to be so long-winded. I've done so much thinking on this subject, due to multiple job losses of my own. I know the whole ordeal is very painful. Don't internalize the rejection. (That's probably impossible, but understand that that is what you are doing.)