My advice would be to lower expectations. Ultimately you don't actually need to pass, you can re-take it. I would view completing the test as the measure of success. With anxiety even doing stuff like this is exhausting and difficult, that should be your goal. Completing the test is your success... view it as a practice run.
This will likely reduce pressure as well, and probably increase your chances of passing. Increasing the stakes of something rarely improves performance. Just completing the test, at all, should me your measure of success.. when you do this, and its fine, you will find it easier the next time. Plus you might pass it as well, so all good.