my nan has been diagnosed with brain cancer - I don’t know what to do

I have been fortunate enough to have three of my grandparents throughout my entire life. Now my nan has been diagnosed with a form of brain cancer today. We don’t know how severe or where it originally stemmed for. We’re waiting for more tests to tell us, but it will either be this Friday or next. I feel numb and I’m constantly crying, it all feels so isolating and the tumour is causing her to feel so disoriented, it’s horrible to know she’s feeling like that. They told us they had limited option but I can’t cope with the unknown. Does anyone have some coping mechanisms for me to try calm my anxiety.