I've literally just passed on my 4th time, I was a lot like you're describing, uncontrollably nervous, the thought of sitting the test once its booked really takes it out of you and you feel like youll inevitably fail it because every time you fail it seems to become harder and harder. But fear not.
What you should do is forget about your previous tests, focus on your weaknesses and strengths and treat it like your real test and the previous were mocks.
I found it very helpful to take some anti stress medication, you can pick some stuff up from a chemist, it takes the edge off although you are still somewhat nervous
Chew some gum or a chewy sweet, it detracts some procrastination for the chewing and the taste as well as takes some possible shaking.
Take your time, even if you risk hesitating, you can have 15 minors, but no majors, if theres even an outside chance of a major occurring don't take it, just wait, times on your side.
Best of luck, I really feel for you. You will pass eventually though. Just keep going!