Depression

I am depressed. There are days like today where I spend every minute in bed. I go to sleep wishing I didn't have to wake up. I am not suicidal, but days like today, it is a very fine line. I feel hopeless. Alone. Lonely. Crippled. Worthless. And no matter How much I know these things aren't true, when this heavy weight comes upon me, they feel like the only things that are true in this world.
I get the most dark, disturbing thoughts flashing through my head, that I feel like I can't escape them. I think of all these ways to escape this feeling, but I am reminded of my kids and how it will affect them. But that is not the worst part of this feeling. The worst part is the battle in my head to convince myself I am wrong and that my kids need me. That I will be missed.
My impression of reality is so skewed that I feel I have hit so low I can't recover. But I do. I do every day I have something going on, out of necessity.
I continually am asked why I don't slow down and cut back on what I have going on, but I can't. It is when I have nothing going on, my kids have their own plans, I don't have work, or school, or anything else I have committed myself to be somewhere, that I get this low.
And it isn't a planned thing, or even sudden. I think how nice it will be to sleep in for once, and then I wake up and I see my kids all have plans, and don't need me. And I think I don't have to do anything. And I just go back to sleep, feeling useless, and alone. And then I have no one that really cares about me. No one checking on me if I am ok. No one invested in my well being, except me. And that is the most empty lonely feeling I have ever felt. I know there are people I could reach out to, but it is hard to admit to your own shortcomings. Especially when you already feel you are pitied by everyone who knows you.
I try to come across as confident, and sure of myself, and strong for my children. But it is tough when the walls seem to keep getting broken down, and you are the only one trying to build them up. There are always cracks, and holes that doubts can slip into easier each time.
Help.