Depression Support Group
Depression is a real and debilitating condition that is often misunderstood by family and friends. Its meaning can range from a prolonged period of sadness to an actual mental illness with specific symptoms. Find and share experiences with others who are going through the same struggles.

Trick is to stop the bus and change the wheel because high speed crash can get messy. Ask me how I know this... ;)
I tend to think that to be a failure you have to be dead. Because until you're dead, you can change the situation. Until you are dead, you can fix things.
My gut feel is you carry a lot of guilt and you're not processing it at the time. Alcohol certainly is famous for helping people avoid processing guilt. Alcohol is famous for helping build that beaver dam upstream to hold more and more unresolved emotions till eventually the dam breaks and it all turns to custard.
You need to start removing those logs one by one. You need to pick something you feel bad about, and sit there, and feel bad. Feel bad till the bad feeling is all felt. Don't think. Don't talk. don't let your brain get in on this. Just feel it, cry if you need to. Cry it all out.
At the end of the process there should be a kind of rest. A state of peace. You have accepted this thing you did, and learned what it was trying to show you.
Feelings are trying to teach you something so if you block them, you not only create the pressure buildup of unresolved emotions, but you also don't learn the things you need to learn to not do them again.
It's a really organic process. So organic nobody gets taught it. So we all have to reinvent the wheel every generation.
I have felt this way all my life. I don't expect it will go away altogether. I am reading a book, After the Tears, about adults who have been raised in alcoholic or dysfunctional families. I am beginning to understand why I have this feeling of failure.