I can echo much of the above, not only the anxiety in early sobriety, but fear of going mad that I can remember since childhood... and I've had my moments, substance-induced and not...
But more importantly is what I have considered my cure. Meditation on a regular basis, simply focusing on the present moment without judgement, has helped quell my fear - not just of going mad, but fear, in general. It takes time and it takes practice, but it's cleaner than benzos and better than booze.
Chogyam Trungpa Rinpoche says we must experience fear in order to achieve fearlessness. I now consider my past fear as a stepping stone to a better place.