Unitl you define in yourself what is important to you and face the dog head on, rather than letting what has caused your anxiety to fester and eat at you from within, you don't stand much of a chance. As Maxxx and Dave_1 have mentioned, realising you have a problem and admitting too it is the first step. 2nd step is to confront it and talk about it to people who you know will listen and care. 3rd is to get the assistance you need from professionals.
Believing you can deal with it is simple. The fact you are not does not even enter your mind. You do believe things are under control. What you do not see is the pain and anguish that it can cause to your loved ones because of your actions that you believe are quite normal. Their not!!! And you are not dealing with the problems even though you think you are. I caused my family all sorts of heartache for those very reasons. That was until I snapped and realised that I had not beaten the black dog, it in fact had me well and truly by the throat.
Sort help, reconnected with the family, got away from that which was a big factor in my problem and couldn't be happier. Still dealing with things, but find it a lot easier now. Oh,, and the happy face is now one that is fair dinkum, not the forced one that is there to mask everything else. Although if you were to ask my wife, she would insist that a permanent frown is not necessarily a happy face. But it certainly appears way more often than it used to.
Depression is not the easiest thing to indentify because it comes in so many forms. It is not just the person who had withdrawn from the world, or has taken to the liquor cabinet a bit more than they used too, or have found a new friend in fast food, or has started taking meds that they were not usually on and any number of other symptomatic signs. Could be singular, a combination of a couple, or the whole bluddy lot.
I don't believe you ever really recover from depression, unless what caused it has been totally eradicated from your memory. If the memory is still there, then so is the depressive trigger. But being happy in your life and believing/understanding that you have dealt with the problem is a huge step in keeping the dog at bay for a long long time. Hopefully forever.
RIP Charlotte and the 1,000's who circum to depression every year.