What do you mean my liver is fat?

I'm not coping well with my life today. I was out sick for several days last week due to severe pain in my upper abdomen and back. My doctor and I thought it was my gall bladder and I was mentally preparing for surgery. Nice and simple and done with, right? WRONG. My doctor ordered an ultrasound on Wednesday morning. Afterwards the tech tells me the scan is negative for gallstones, go home and call my doctor tomorrow and it was only 9 am! After leaving two messages Thursday morning I was finally able to speak to my doctor late Thursday night. He informed me that I have "Fatty Liver Disease". What the h*** is that??? OK, so I need to lose a few (read: several) pounds. Apparently there is fat IN my liver, which is a bad thing and can lead to all sorts of not-so-fun complications such as cirrhosis or cancer. There is no "medical" treatment for this, the only thing I can do is diet, exercise and avoid alcohol. Yes, I should be doing these things anyway, and was planning to...see my New Years Resolutions. I'm just having a really hard time wrapping my poor little brain around this new diagnosis. You see, I have previously been diagnosed with SEVERAL other disorders and this is just ONE more and I'm wondering how many diseases one person can reasonably have. Maybe I shouldn't ask, the doctors might come up with another one.