Hello Depression

So, I guess I'm experiencing depression for the first time in my life. I've been through hard times before - watching my father die of cancer, helping my sister through chemo. while she had three small children at home, etc. But, during those times, I remember clinging strongly to some of my usual enjoyments in order to maintain a sense of normalcy. Right now, I have no idea what normal is. I don't care what normal is. I don't want to be with anyone. I don't want to do anything. I can't make sense of anything. I struggle through my work days, more distracted than ever. I come home, take care of a few chores and then collapse sobbing. I try to sleep, but invariably wake up after a couple of hours and then toss and turn for the rest of the night. How long can this keep up?