if you're really feeling like you're going to hurt yourself, get yourself to a hospital asap. there is no shame in spending time in an acute unit if it saves your life. dont wait until youre in the grip of an episode. just go. the only thing you should die of is old age.
also I would try to see a doctor or psychiatrist who can asess you more thoroughly, and perhaps put you on medication to stabalize your moods. :)
There is help out there. These things you are feeling are horrible to have to feel... but remember these feelings will pass. It is a terrible thing- being deprssed. I have been there many times and felt I had hit the bottom, but with treatment I have come out of it. I know there is hope for you. Please call your therapist or doctor if you feel that you may do something to harm yourself.
Please don't take any actions. You have a purpose here you may not know what it is today but someday you will. Try to reach your therapist and keep as busy as possible. I know just a change of space can sometimes trigger a mood change. Getting a job or volunteering is a great idea do it today get ready and act on it and focus on doing that until you make one positive step in that direction( just find a phone book and make a list of places you can volunteer) even if you don't accomplish it today it may help to focus on doing so. So sorry you are feeling so awful. You are not the first to feel this way and you will get through this!!