I'm really sorry to hear your news. You must both be really shocked & scared :(
Try your best not to google - it doesn't do you any good.
You asked how you should deal with this... my advice (for all it's worth x)...
Try to spend as much time together as you can and with friends/family if DH is up to it. Talk. Remember all of the really good times you have had, laugh about some of the stupid arguements you have had and tell each other how much you love one another.... say anything and everything you think is important. Do the things you love to do if he's up to it.
Get all of the horrible, practical, hurtful things sorted out as soon as you can (your wills if you don't have them in place), sort out anything that is in DH's name alone, discuss what he would want if he died (funeral, for you for the future, practical things etc). Ask him to write some letters for the DC, take lots of family photos etc It is scary & horrible to deal with - but you will both feel better for doing it and once you have you can put it behind you and focus on life one day at a time. Of course, the chances are you wont need any of those things - but it's a load off of both of your minds to have it sorted.
Once you have done that, focus on the fact that they can deal with it now they know what is wrong. Someone sadly has to be the 20th person who doesn't make it through the operation - but it is far more likely to be someone who is compromised in other ways - be that other health issues or old age.
Keep posting x