I've been getting progressively more depressed over the last year. I'm planning on going into therapy. But I want to know how much I should say to my wife, kids and friends about what I'm going through. Everyone pretty much knows what's going on with me, but sometimes they watch me a little more closely and ask how I'm doing with a little more concern than I'm comfortable with. I'm not sure whether to open up or to clam up and tell them that whatever I need to talk about will get talked about in therapy.
Consider talking to friends and family about your depression if you see them as able to be supportive. Thus far, it sounds like they have been—to their credit. Those close to you have already noticed that something worrisome is going on with you, so it may be best to help them understand what it is. You can educate them as you educate yourself about depression, what you're doing about it and what they can do to support your efforts to recover. They can't do your therapy work for you, of course, but they can certainly support and even participate in it sensitively.
If, however, your family isn't supportive and will only label you negatively, be careful about disclosing what is going on. Opening up is generally a good idea, but not if others will use your disclosures to judge you badly or make things worse for you. You don't want to defer family decisions and avoid family responsibilities because of depression. You don't want to train others to see you as sick or fragile. After all, you won't be depressed forever.