Dear UK wife,
It sounds like your husband has been having a very good quality of life since being diagnosed, and that is wonderful. Please don't have worries that you didn't try chemotherapy earlier, and don't feel guilty, as your decision allowed your husband to have a pretty normal existence, it seems. It's an individual choice and there are no right or wrong answers. I always have to say that to people because I know that there are some people who have benefited tremendously from chemo -- in my mother's case, chemo was a bad idea and I wish we had never tried it. But everyone is different, and we're all groping for answers in the dark.
As for your husband having no symptoms, that sounds like my mother's experience. Please don't let the fact that she died influence you - this disease progresses differently in everyone. My mother had intrahepatic tumors on both lobes and I guess it didn't interfere with her liver function until near the end - never needed stents or anything. Her only symptoms were fatigue, dull pain in the abdomen and abdominal swelling - when these started to get worse and she was nauseous all the time, she tried chemo and it really weakened her immune system, which was not too good to begin with. She was allergic to many drugs and had autoimmune disease, so that is partly responsible for her not tolerating chemo well. I think the chemo actually hastened her death, so it's a really tough call - some people would have their lives extended by chemo.
I would take into account your husband's strength right now and his tolerance for drugs - we all want the best quality of life for our loved ones, and it's so hard to know what will make that quality better. As I told my mother, you can always try chemo and see how bad the side effects are, and then quit if you think it's too much. You can just give it a trial run if that's what you want, and make sure you get anti-nausea prescriptions and pain meds for side effects and the natural symptoms of the disease.
I wish I could give you better and more well-informed advice - I'm so glad that your husband isn't in that much discomfort, but I know you're just waiting for the other shoe to drop and it makes you feel so helpless. Please know that whatever you decide to do is the right thing and your love and support is more important than any medical intervention.
I wish you all the best and hope your husband stays healthy-