I'm sorry to hear that you are going through this.
I lost my dad 18 months ago to acute myeloid leukemia. His health deteriorated suddenly, in under 3 months, before my sisters and I took him to the ER. He was in the hospital for 2 months, and received some chemo; it was terminal, and the only thing that they could do to help was give him blood transfusions to up his cell counts (which failed to respond to the drugs that are meant to do just that). He decided to stop any further treatment. Three weeks later, he passed away. So, at age 25, I was parentless.
To see him deteriorate, to see him suffer... Right now, all I can think of is watching my dad go through this... I'm not sure what else to say, other than my heart goes out to you and your family right now. It's not easy, and it hurts like hell.