So, I don't know if this will help, but I went through something like this some years ago as a consequence of some post-traumatic stuff, and found that walking meditation was easier than sitting meditation, though finding a safe-feeling spot to do it was challenging. (I ended up taking five or ten minutes in the room I was taking a yoga class in, which was empty afterwards.) In retrospect, I suspect that a still more physical approach... e.g., doing mindful situps, or something like that... might have been even more useful.

I also found that the anxiety itself grew less crippling over time spent attending to it and focusing past it.