Could it be because they're all afraid of him? As in, the first one to go against his wishes will be made an example of?

It sounds like you are one of the first, and everyone in the family has a big investment in proving that you won't get away with it -- because if you do, it'll mean that they could've, too, and all these years they've been putting up with his abuse, and (I'm guessing) one another's, for nothing. They seem to be trying to make you the "identified patient"; I'm pleased to see that for the most part you're having none of it.

You seem to have grown, and gained a lot of perspective on your family situation, since your other thread almost a year ago. I'm sorry this has to be so hard on you, but I think you're doing the right thing setting boundaries and distancing yourself from the whole mess.

There's one thing that I wanted to be sure to point out to you: if you set out to succeed or fail (at whatever) in order to prove your father wrong, your life will still revolve around your father. Whether you succeed or fail, let it be at something that you choose for yourself.

I don't know why I'm even asking, but is that aunt your father's sister or your mother's?

That is how it's going to look when you adopt your father's perspective. You already know his is not a good fit for you; you do a lot better when you're looking from your own point of view.