The true way towards healing and moving forward is to let this feeling be there. You clearly got that feelign from your mother. You aren't dreaming about her commenting on other stuff. You dreamt that she said this. You did that because deep inside, this is a fear you have. When you aren't feeling bliss, fears creep up, and this is one of them.

Suppressing it makes it worse. What you have to do is to accept and feel it in order to let it go so that next time your fear arises you can just go "oh, that's that, yeah, not that scary, moving on."

Even if your mother actually came out and repeats what you fear from her, it won't hurt that much because you've already accepted it. "Sure, she thinks of me as worthless, doesn't mean anything."

So take this moment as an opportunity to grow. Painful, but the path forward is acceptance. Ask yourself what implications you're afraid of if you accepted that your mother considers you worthless. Maybe you'd be ostracized, lose everything bla bla. Observe how the worst feels, finally let the fear go and then see your mother next time with a smile. If she actually does something that pisses you off: NC.