I understand. That is unfortunate, my condolences.
I actually came across a similar scenario recently. There are people who refrain from telling loved ones to spare them the trauma. However you can imagine that the loved ones who were kept in the dark, sometimes resent not being told what's going on. But like you said, your family will find out eventually and I can understand why you choose not to say anything. You are very kind and considerate.
So like you said alternative support for cancer patients, I hope the advice I gave you is sufficient and I'm glad that I could help! There are going to be bad days, but the good days afterward should more than make up for it! But like I said, you're not alone in this, and if you need help just ask and you'll receive it.
“Happiness can be found, even in the darkest of times, if one only remembers to turn on the light.” - Albus Dumbledore
Friends are also a big help, but cancer does however weed out your fake friends from the real ones and good riddance too! But you will also discover that people you didn't realize cared, have your back, you will find that you have friends in many people. And you'll make more through this cancer 'experience', through the hospital, forums, treatment centers, etc.
I should also mention that no one will really understand what you're going through unless they are going through cancer too. Be patient with people though, they try their best to comfort you and often don't know the right thing to say. Cancer is a one man battle.
We're young though, our odds are significantly better than most cancer patients, but attitude is just about everything when it comes to winning this fight, so keep your chin up at all times!! (Btw, cortisone/prednisone can make you temporarily depressed, but it passes quickly when you stop using it. Just so you're aware. I had it and it is important to remember that it passes!!!)
Best of luck with your grandmother, family and your own battle!
Please check in and keep us up to date with what's happening