It's good to keep a diary like this. I did this a while back using a false name, I wrote down what I was feeling and thinking. But of course there is that danger that someone will 'out' you and I wasn't ready to let the world of Mumsnet in on my personal life to that extent.
I've been through similar although there is no one thing in my life that set me off. I've been having problems with family, I left a job that zapped my confidence, I have a new job to start in Sept, ds has a new nursery that he hates and screams every time we pull into the car park, I have both kids during the hols, I've had to organise a big do for my dad which, during the current family state was very stressful and not at all easy, and I think all of these things just came to a head. I started to get paranoid, thinking people were talking about me. Even on the street I thought people were looking at me and whispering. In those circumstances Mumsnet is not a good place to be! I had mood swings, so I was angry, then happy, then weepy. I couldn't cope with everyday stuff like ds being ill, it just became a huge trauma for me, everything became a huge trauma. I also got confused, I couldn't remember dates or appointments, I forgot to collect dd from school once, I forgot to eat, I would start to drive somewhere and forget where I was going or even more worryingly, which side of the road I was meant to drive on. This just happened yesterday too, but I'm hoping it was just a blip.
Thing is, you have 2 choices. You can either sink into that hole and let it swallow you up, surfacing every now and then to wallow in sympathy. Or you can give yourself a good kick up the arse and do a 'get out of jail' plan.
I wrote down everything I had to do every day and I did it. It's working. I'm getting better.
Pills are ok. But beware of just taking pills and doing little else. Yes depression is an illness, but it also has a cause. It's like going to the hospital with a broken leg and being given painkillers but nothing else. The painkillers mask the symptoms of the broken leg but once you stop taking them, the leg is still broken, your situation is no better.
If it is helpful I can tell you what my plan was and you can adjust it according to what works for you. But you need to get yourself out of this, no-one can do it for you. You need to work some tough love on yourself, get mean and you'll start to get better.