Slogging it out

I'm trying really hard to keep a positive attitude but it's tough. I know there are people in far worse situations than me and that I am lucky and should be thankful...
1) My job SUCKS. Everyday someone else jokingly says "bet you're glad you're doing this eh?" Um, if you would a bullet to the head over my job what makes you think I'm any different?
2) Writing cover letters is... less than fun. Especially since it's unlikely the 5 trillion of them I've written are actually going to get read by someone and lead to a job. Very disheartening.
3) I hate the person this is turning me into. I'm becomming bitter and angry and every time I open my mouth a torent of whining and complaining comes out. This post is a perfect example.
4) I'm tired. All the time. I want a life but I don't have the energy to live one.
5) The chances it will get better soon are small. The promotion I was going to get? There have to be people in the group to supervise and we're 6 people down and on a hiring freeze, which leads to... no chance of taking vacation because no one can cover for me. The only person at work who understands is about to leave for maturnity leave until FEBRUARY. I can't move internally because my team won't let me leave and no other team wants the bad feelings... and externally... what company really looks at the resumes they get over the internet?
6) The previous 5 points have affected my motivation and performance. Basically, I don't give a damn anymore.

I haven't felt this trapped, frustrated, angry, unchallenged, and miserable in a long time. It actually reducing me to tears annoyingly frequently and I know it's giving me a vile aura. I used to be happy and energetic and goofy - I want to be like that again. Everyone says there will be times in your career that are less than ideal - times when you don't like your work or where you live, but this is stupid. I'm MISERABLE.