Overwhelmed :(

I am totally overwhelmed...and depressed. And my bucket is empty. The thing is that I don't act depressed when I'm around people who aren't my family. But when I'm at home, by myself, I feel like I'm a failure. My house isn't clean and organized. My children aren't nice to one another and they don't get their homework done and/or one has theirs done and wants to play and the others need constant help to stay on task. It probably doesn't even sound like it's all that bad, but when I'm depressed, I can hardly finish a task let alone start a new one. It feels like everything needs to be done at once and it's hard to put things in priorty order, especially when children are whining at you about something they want. So I often end up giving in to their wants to have some peace and fun, and then other things don't get done and I end up feeling even more guilty.
I would like someone to just listen to me. I know that I can figure out the changes that need to be made. I will press on and try to correct my mistakes. Is it ok to mess up over and over and over if I continue to get up and try again? Am I still valuable even though I hide from things that are hard sometimes? This life is hard! It stinks a lot of times... But I haven't killed anyone today, and I didn't even yell. I just got frustrated and tried to help them understand. Now I go back to the basics and try again and again and again....