I lost my mom when I was not much older than you. It was not easy and I still miss her 22 years later.

I don't know your situation or the relationship you have, but all I can say is to cherish every moment you have left. Give her all the love and support you can. She's likely afraid too - of what's to happen and of what she leaves behind. Remember the good times you had together and keep that.

And after...let yourself grieve - it's natural. Don't feel guilt for grieving. It's part of healing.