I'm so happy for you that you went and you got help. I've gone twice to the ER for anxiety related to withdrawal. But the first time around I didn't. I experienced what you did. I took public transportation to work and then had such an awful panic attack my brother came and took me home. Stick with your appointment.
Whatever you do, once the attacks pass, don't do what I did and start drinking again. "Hey! That wasn't SO bad! I think I'll do it again." That was a bad idea. You did the hard part. You reached out for help. I've always found the ER personnel extremely kind. Please keep us posted on your progress.