The feeling that nobody cares about me is one of the toughest things I have to take issue with when I am depressed. The more I think about no one caring about me, the worse my depression gets. The worse my depression gets, the worse my self-esteem . . . seems like an endless cycle.
With your wife doing that to you - you definitely need to think of only one thing right now - you! Until you can get yourself back on some kind of track, whatever issues you have in your marriage need to be back burner things. I know that sounds like you're letting things in your marriage go, but you are not. Being married myself and having depression has made things very tense at times. But the more I find I help myself by going to therapy, etc, the more it helps the marriage. As Kitt and MyJoy have said - find a therapist and find one that is good for you. It will make a world of difference as to your outlook on things.
You're not worthless, and you have support. I'm a newbie to the forum as well, and I can tell you in just a few short days, I have gotten some excellent advice, and more so - encouragement. These are some great people here, and they understand what depression is and what it does.
Best, my friend.