Okay. This could be extremely important to you both. Give your feelings about her careful thought. If you find that you do, in fact, love her. Tell her that and tell her that you want to be with her no matter what. Tell her that you are not afraid, because believe me, she is. Tell her that you want to be with her through it all, and then be damned sure to do exactly that. You see what I'm saying?
It's not going to be a picnic in the park. She could die. The treatment is like it is for cancer. You can consider it to be a type of blood cancer. There will be times of remission when she feels really good, and there will be times when she is very, very sick. Are you willing to be there for her through all that? If you are, if you are a strong enough man to do that, and I am in no way whatsoever suggesting that you are not, then go to her and tell her that. But I'm warning you now, loving her will be painful because of the danger to her life. All you can do, because you can't really help her fight that fight, is to stand by her and give her what strength and comfort that you can.
But you have to be absolutely sure. Because anything less will make her fight just that much more difficult. It's the "worse" part of "for better or for worse". It's the "sickness" part of "in sickness and in health". It's "til death do you part" serious. Go to Web MD or other medical site and read about it. Know the enemy so you can know if you can help her win (or lose) that battle. (kiss)