@Rabbitsinmygarden sorry you are going through this. It is horrible. When my wife was diagnosed, I think it was the feeling of helplessness that hit me the most. All you can do is take each day as it comes, each bout of treatment as it comes, and each diagnosis as it comes.
I agree with the above in staying away from Dr Google, that way lies madness. At the end of the day, none of us know how long we have left, and my suggestion is to do the things you've been putting off for 'one day', use the things you've been saving for 'best', make memories, talk about the things you've done together, laugh, cry, hug.
I hope that his outcomes are positive, but if they are not, there will inevitably be a day where you may wish you'd said more, done more, hugged more. I know this as I lost my wife to cancer last year. There isn't a day that passes where I don't think of her, and wish I'd told her more often how wonderful she was. I did that a lot, but it just never seems enough. Of course, even if I had had the one additional conversation, I would want another, and another, and another.
Try and stay as positive as you can be. It is very easy to slip into a depressive cycle, and the reality is that there are many treatments now that didn't exist even five years ago. Nothing is certain until it actually happens. My wife made it longer than her prognosis.
Big hugs from a stranger in the ether.