Perhaps instead of focusing on the outcome of the AC, you could view it as an opportunity to improve the 'thinking on your feet' aspect that you don't feel as confident with, particularly as you are content with having DLA. I have done the AC and feel it was quite nice, in that everyone is incredibly friendly and they don't try to trip you up or grill you at any stage. Before each task, grad rec even go through which skills they are evaluating. You did incredibly well getting through to all those ACs, they clearly see potential in you. On the other hand, only you know your mind and what's best for you. If you really don't feel up to it, there's no need to push it; mental health should take priority.