Selena.
First and foremost, if you are serious about being sorry for self centered-ness, standing before a crowd and sad-sacking for them is not a good way to go about changing that. I look forward to highlighting the problems with arguing in your reply.
Second, as I'm sure you noticed, there are a number of people who will reply with help of varying levels of effectiveness to your woes. I, being a beautiful and unique snowflake in every respect, had much the same initial impulse and no desire to change it. We've had the stoic response from Raleigh, and the feel better hugs from Rowen. Now an inspirational blah-blah-blah from me, and then someone else can step in and ask the pertinent questions (how long have you felt this way, have you recieved help, do you feel like nothing will ever change, how much wood could a woodchuck chuck, etc.)
Depression is a natural part of life, particularly when something screwed up happens. Sometimes you need to sit down, stare at your toes and figure out just what the bleep happened here. Sometimes you don't. And while there are any number of people happy to tell you what to do when, you're best off answering that question yourself.
That said, should you find your attention wavering from what you want to do to 'I suck, the world is bad, I'm going to go listen to Johnny Cash and paint my toe-nails black,' please consider the following.
The brain, being primevally a reflex organ, forms connections easily and lets go of them slowly. If you find any number of things slowing you down in your shift from 'bleh' to better, that is normal and no valid reason for giving up. If certain things trigger sadness, apathy, lack of emotional connection, etc, do not do them. Barring important things like eating, brushing ones teeth and the like, often such things are easily avoidable and unnecessary. If you don't like driving, walk. Or bike. Unicycle there, I don't really care. It is entirely up to you how you should live your life, and if you don't enjoy doing something one way, you certainly have the power, privilege, and opportunity to try it another way.
Since the mind is loath to let connections go, you can employ that to trigger some happiness in yourself. Something as simple as a favorite joke can make the load a lot lighter, and if you can tap into a memory of accomplishment, the problems grow small indeed. From personal experience, any moment will work. For the longest time, I would just whisper 'sugar snookie' to myself to calm down.
Get some music in your life. This can be anything from humming a favorite song to going to a concert. If you can make sound effects, beat box when you have some time. Make a bathroom stall into an impromtu drum set. The whole reason musicals tend to be considered trite upbeat smile fests is because it's so damn hard to stay glum and motionless when there is a rhythm whispering through your blood.
Oh, and if it has been going on for as long as you say... get help. Seriously.
Da list; Sakraida82, Cow Bell Man, Resident E.V.I.L.