What is a word to describe miserable and happy and the same time?

I've had this feeling all of my life, it comes and goes. I feel depressed and dark, but I also feel content with it, and like I can't be happy unless I'm sad. I feed off of pain and feeling depressed or cynical. When I feel like this I also feel more happy that I would if it was pure happiness with no sad feeling at all. Is there a word for this?