I really think you're catastrophizing their control because of your fear. And that is perfectly understandable. But don't assume that the scale of your feelings reflects objective reality. Your assessment of their control is being fueled by very powerful childhood fears. Of course, the possibility of all sorts of reactions is there, but the liklihood of those actions happening is very different, and not dependent upon your current feelings.

You don't need your parents' permission to not speak to them. That's your fear talking.

Try to step outside of your feelings for now. Put them in a box and distract yourself.

Get through the next days, and then work with your T on a plan to become financially and emotionally separate from your parents. You can do this.