Anticipatory grief- losing sight of the future , feeling lost

Hi

1. Husband been diagnosed terminal S4 met lung 10 months ago out the blue. On treatment but latest scan says its spread further in the brain. Now worried the next scan will say it's spread elsewhere and brain is the least of our worries.

We have 3 children under 5y, youngest is only 8 months old. 

We nearly lost him once already before they finally accepted him onto the trial as last attempt. 

I'm worried it's happening again and just can't seem to focus on enjoying the time together now as I'm so worried about the future. I know I need to cherish this time but the anxiety of what's coming just won't let up.

Anyone found this? If so how did you stop it? 

Thank you