Hello whenwillitend,
I'm afraid I have no words of advice to give you, because I have been in your situation before and know how horrible and hopeless it feels. I also know that cliche sayings like "it's always darkest before the dawn" are probably meaningless to you at this point.
But I will say that those deep depressions do not last forever. Especially if there is work being done to combat it - meds, therapy, healthy eating, exercise, and/or other methods. Just like happiness does not last forever, neither does depression. Our emotions are constantly changing - so please keep in mind that you will not always feel this way. Hang in there, it DOES get better.