Exactly what you're doing. Being there for her, listening to her. And as Jean said, take care of yourself. That will give you the strength to be strong for her when she needs you.

As for low carb helping with cancer, I haven't made up my mind if that actually works. But I did decide that should I get cancer, I'm going to go zero carb. Even if it doesn't help with the cancer, it would help me feel like I'm doing something positive to fight it. All the medical things that fight cancer are provided by others & can make you feel helpless. Doing something - anything - can help you feel more positive.