Rant away. We can't only come on here when we are all jolly, it would be unnatural. We need each other and that is the beauty of GN, to help each other through all the times, good and bad.
I have had bad spells of depression too. I think once you have suffered with it, it stays with you and rears it's head from time to time, just when you least expect it. It is like a dark tunnel, from which there feels no escape. Mine has all been family based, but I have had counselling and felt better after it and have somewhat coped better since, even though things have upset me and continue to upset me still. I reason things out for what I want out of my life, not what is best for anyone else anymore. I have done my best for everyone in the family and when I and my son were going through a particular bad time, we only had each other to get better. No-one else wanted to know. So now I look after him and myself, everyone else can go spin.
I don't know your full history, but I found that doing really small things like painting your nails, soaking your feet, having a foot rub, someone brushing your hair, massaging your hands with lovely hand cream, all can make just a little difference and slowly lift the spirits again. Do you like reading? I read Chicken Soup for the Soul books and they make me feel good. Have a look on Amazon, you can get one for £2.81.
I do hope you feel better or at least a bit better soon. It is awful and I know what you mean by your DH dealing with it. My DS says the same when I try to explain yet again how I feel, but he still listens and makes me feel better by his young wise words. I'll be watching for your progress. 