I Think I'm Depressed

I feel like all this time mu happiness was hanging over the edge, threatening to fall back into the dark recesses of my tortured mind. And tonight the string finally snapped, sending me spiraling down into the black hole of my thoughts. The depression, the cutting, the sadness and fear, its all flooding back at once. But its so much harder to bear now that I've tasted the bittersweet feeling of happiness. All of that seems so far away again, like a fog is covering it from me. Preventing me from getting back. I need to get out. I need to escape. But how?? I'm trapped.