Sandy, I just saw your note - and it has been some time since you entered it - so I don't know if you are still following this. First, my thoughts and prayers are with you. This must be one of the most difficult times of your life.
I was the primary caretaker for my father in 1991, my only sister in 2002, and my mother in 2003. Each of them lived about two years after being diagnosed as terminal. Each of them faced their diagnosis with such grace and courage, but only my father conversed with me about it a lot. My sister talked about it at times, and my mother almost not at all. So, in retrospect, I learned that every patient will deal with it differently, and a caretaker would be doing a loving service to the patient to listen carefully and let it be OKAY, to talk or not to talk. They will let you know what they prefer. And if they ask you hard questions, try to be honest and genuine, but loving, in how you answer.
During each of those very sad and frustrating terminal illnesses, I experienced what you explain as anticipatory grief. At times, it settled on me like a very heavy, dark cloud - and because I am normally a very optimistic, take charge, upbeat person, it frightened me that I was falling into sad, muddled, futile spells. At times, I awoke from a deep sleep, sat up in bed in a panic, knowing I was losing them and there was not a damned thing I could do to change it. At times I kind of hyperventilated and felt like I could not breathe, because I was so afraid. In retrospect, I think I was suffering from depression, but I never put that name on it at the time. I worked through it by making it a priority to bring something cheerful or beautiful into our lives (mine and my patient's) every day - sometimes it was beautiful music, sometimes a bouquet, sometimes just spending time sitting in the room with them and talking about their childhood or something to make them smile.
I almost forgot to take care of myself. I lost my appetite, and meals were no longer a celebration, but something I rushed through because I was rushing through everything. Once I was so stressed when both my mother and my sister were in the same hospital - with no positive news on either of them - I checked myself into the ER, certain I was having a heart attack. (I was a 51 year old woman in excellent health.) The doctors checked me for 4 hours and said I was in perfect health but experiencing a panic attack. So, my advice to you is: remember that you are important to your loved one and you need to keep yourself healthy for them - and recognize that you are only human, you are doing your best, and you MUST care for yourself now, not "sometime in the future when the situation changes.". Find a way to calm your life for a few minutes each day: meditation, yoga, nature walks, whatever you love. Eat healthy food and drink only a little alcohol. And try to sleep at night, even if you are so worried that you have to move your bed into your patient's bedroom so you feel like you will be there, if needed, but you can also get some rest.
You should know that, this too shall pass. You don't want to think about that now - because it means the terminal illness will be over. But, just put the thought in the back of your mind that life does move on, humans do recuperate, and there will be blue skies again some day. It will keep you from thinking all is lost.
Two things happened to me after each of the illnesses were over: 1) I wished I could talk with them again, hear their voice. I feared I would forget too many things about them. This makes it all the more important to talk with them, hear stories about who they were in their younger years, tell them how much you love them and what a gift they have been to you. 2) I carried my grief with me everywhere immediately after my loss. Finally, I told myself that, each time I remembered them, instead of starting to cry, I'd force myself to remember something wonderful about them, or a joke they had told, or some really sweet, outrageous thing they had done - and smile about it. It was difficult to do this at first, but once I got it going, it helped me immensely.
Finally, know that there are people in your life who care and truly want to help you. They may not know exactly how to help, and they may feel awkward talking to you about what you are going through. But, when someone says, "I am so sorry for what you are going through. How can I help?" believe they mean it - and think of something they can do that would lighten your load or light up the life of your loved one.
Best wishes. We are all thinking and praying for you.