Laura,
I'm so sorry that you are going through such a rough time right now. I went through a very similar time a little over a year ago. The anxiety was constant and I had several panic attacks a day. I wouldn't leave the house and was terrified to be alone. I've had all the symptoms you are describing as well and felt like I was totally losing control over myself, my life, everything.
Have you ever read any books by Claire Weekes? During my bad period, I read her books constantly and it gave me a good understanding about what was going on with me and what I could do about it. It does take work, you really have to keep control of your negative thinking and allow the feelings to be there, but in time it does get better. There are alot of other books on the subject as well and I'm sure others here on the board will have more suggestions for that. Keep working with your breathing, and positive thinking it will work in time. If you need some support, you can e-mail me anytime. You will get through this, hang in there and let me know if I can help.