I know how you feel for part of what you said Spaceid. In the last half of the past year I was dealing with trying medications and school and figuring out that I have a gluten intolerance, and I just got so angry with my depression. In a way it did help me though, as even when I was in a down period I was thinking things like "I can fight this" "Go away!" "I don't deserve this.". Maybe you can use that anger to try and fight those sad feelings. They won't necessarily go away, but it may help you do things instead of putting things off or what-have-you.

As to your relationship issues, I know it's hard, but you were able to cope and have fun without a relationship before. You will again. It will take time, and you may feel like the pain of missing that person will never go away, but one day you'll notice that it's easier to think of him. You deserve the commitment that you want. *hugs* I'm glad that we can help you as well.
I wish you the very best!