This sounds so much like my son Scott, 23 and been given months or if we lucky only 2 years to live. i do not think there is any right way to deal with this. Although I have been through cancer with my dad, brother and sister there is no advise I can give you to help, Just be there as i am sure you are for your husband as he needs to feel love as much love as you can give him and my advise to you is lean on family, you to are going to need support as he might be the one with the horrible illness but you will be going through it with him.
I am praying my son/nephew will get through and prove the doctors wrong and I will pay for you husband to. You need to both enjoy life, and never give up hope, keep serching and looking for new treatments and talk to you doctor about them even if they sound really unhelpfull.
Now saying all that I hope you are not my son/nephews wife.
Nothing you do will prepare you for the tough times ahead. I have found that out by experence
regards maryann