You do sound like you are depressed and I agree that you need to see your GP - it does take a bit of courage I agree, but did you know that one third of all GP consultations are related to mental health, and that 1 in 4 people will suffer from a mental health problem in their life. I have had 2 major episodes in the past involving inpatient treatment, and it was the ADs thats saved me really.
The thing is with depression and anxiety (as they usually go hand in hand) it does fluctuate from day to day and even through the day. I sometimes feel crap in the morning and get better as the day wears on, others are better in the morning. These fluctuations are the nature of the beast. It sounds like your anxiety level is quite high too, given what you describe what happened this afternoon
I can see that you hate the idea of being depressed as you have always been the practical, sensible one, but you know anyone can get depressed, no matter who they are. I was a middle manager in social services and was competent, confident and caring and my best friend died and WHAM I was an emotional wreck. GPs get depression themselves.
Maybe write down a list of your symptoms in bullet points. I felt for you so much reading how you used to be (and you will be that person again) but you need help. When I was in hospital I remember drawing a picture of the "old" me (all pretty positive stuff) and the "new" me- all crap stuf.
Just one other thought - you mention these nervous tics - I think you should include them in your list of symptoms. They sound like they have their root in anxiety. Sorry your DH doesn't understand. I truly believe that no one can understand the torment of this illness unless they have experienced it for themselves.
Finally do remember that you won't be telling the GP anything he/she hasn't heard hundreds of times before. SO go on - pick the phone up in the morning and take the first step on the road to recovery...........