Not sure if you will read this before or after your trip, but either way I want you to know my prayers are with you and I hope for a miracle. Cherish the time you have together, and I'm glad you took the trip together.
We lost my mom in 1996, at the age of 50, to lung cancer. While it was only two months from the time she was diagnosed to the time she passed, she had known for a good deal longer that she was sick. However, like you, my family only had months to deal with the shock, pain, and anguish. As tragic as the severity of your fathers condition is, it may be better that he hasn't been able to go thru radiation and chemo. We took my mother thru all the radiation, and in the end it just inflicted more pain on a frail body that was going to give out in a short time anyway. The quality of life achieved without the treatment, in some cases, is better than the relatively short, more painful, extended time one might achieve thru treatment. Your trip to Disney is a testament to that. Far better for your father to enjoy some days at Disney, than to be sitting in front of a radiation machine or getting a chemo injection on what could be some of his last, prescious days. I hope you have a wonderful time, and even thru the pain can generate some wonderful memories that will be with you forever. There will be tough days ahead, but rely on each other and the Lord and you will survive them.
I am particularly glad you took this trip together, even though it may be difficult for your father and your family. It is better for him to not sit and dwell on his pain, and if any place can make you forget, if even for a short time, what you are going thru WDW is the place. I do hope nothing tragic happens while you are there. For years I had bittersweet thoughts about Disney related to a trip during the time my mom was sick. My wife and I had a trip planned that year around the fourth of July. After tending to my mother for months and taking her to all the radiation treatments her tumors were shrinking and she seemed to be stable, depite tha fact that she was becoming more frail and required more and more morphine. She encouraged us to take our trip, and assured us she would be ok for the week we were gone. My brother, a nurse, was there to care for her, and she wanted us to be able to get away and enjoy ourselves. While we knew it would be difficult to do that given the circumstances, we did decide to go. That is the one decision in my life that I regret to this day, as we got the call from my brother on the fourth that my mom had died. I always wondered if I could feel the same at WDW again. In time we were able to put that painfull association of Disney and that moment behind us, and I later came to understand that that is where we were supposed to be at that moment and that my mom encouraged us to take the trip for her own reasons. A couple of days before my mom passed she was admitted to the hospital. My brother slept by her bedside the first two nights, but on the last night my mom insisted that my brother go home. She knew it was time and she wanted to let go, and didn't want to have us there to make her hang on any longer, and she left us that night. Anyway, I'm glad you took the trip together and no matter what happens I'm sure it won't be a choice you regret.
No matter what happens, know that you are not alone. Hopefully knowing that, and knowing the experiences of others, can help provide some solace and comfort in this difficult time. Enjoy your time, enjoy your trip, and God Bless.