ditto what limey said.
I have no idea who you are either---but I can tell you one thing I know for sure: things change. Friends, family, jobs, children, houses, neighborhoods, luck, feelings; it all changes - those things and more.
You won't always feel this way. You need to find someway to handle the stress of NOW (I color, draw, journal, read and talking a walk in the park is remarkably restorative) paint, write wicked kick ass poetry, punch your pillow or buy some inexpensive dishes and smash them somewhere safe for you and others. And scream.
also write to us here b/c there's a whole lot of us hating this fucking January. Maybe the world SHOULD have ended 12-21-12 and we're just living in the nightmare of the aftermath of what should have been but wasn't (I blame the Christians for this)