The liver breaks down all the drugs in the body, so it looks like the morphine and all the pain meds may be having an effect on your liver.
Ironically, it does take about 15 years of things like 'hard drinking' in your case, loads of meds, to do any significant amount of damage to the liver.
Fatty liver can also be related to diet, if you eat a lot of sugar or high GI carbs............And
The liver does have a remarkable capacity to regenerate.
You will have to give it a rest though, so it may mean finding another means of pain management.
Have you also been taking any paracetamol?