Thanks for your answers. Unfortunately, I'm in an open plan office and the interview, tho only brief, was held by the head of my section (not my boss, who, I'm beginning to realise, is quite sympathetic) and anyone could have overheard in passing. He wasn't unsympathetic but I heard myself saying it was depression caused by moving house, money troubles, which is true - just not the whole truth.
The day was okay. I still don't like my job as such but it helped that a couple of people I feel uncomfortable with were on leave and the guy now sitting near me is v.approachable (thankfully, I hassled him all day about stuff!).
The head of my section asked if I wanted to move to another area but it would've been similar work and, anyway, my social anxiety would hit sky high if I moved to new people and situations again!!!
On the plus side, I genuinely think the tablets I'm taking (Cipralex) ARE helping and I had nice phone calls and text messages from family and friends today so I am lucky in having support.