You need to see a counselor now. You may need some time off. Perhaps under professional care.
If you want, take a minute to tell the wife you're going to get help. She'll probably think that's a great idea. She may be trying to think of some way to help, or trying to make sense out of a situation neither of you is to blame for.
Schedule some medical leave at work. You don't need to give them details. If they haven't been observant enough to already know, then they probably don't care. Just tell them you'll be fine. Or, just give them a call after you talk to a therapist.
If this is a cyclical depression, there may very well be a chemical reason for it. If you have a unique neurology, it may affect you in unique ways. I've been there. I had to take some medicine for a while, but life is a lot better on the other side.
Most of all, make contact with someone competent as soon as you can. You don't deserve to feel that way.