My future sister-in-law's got cancer?

How do I reconcile the gap between her and my fiance now that she has got barely 2 years to live? She and I barely see each other yet I am concerned because everytime I talk to my fiance, he has got no feelings towards the situation. He even said that, his sister did not even do anything to help their parents at the time she had the means to do so. My fiance was the only one who took care of their sickly parents. How can I talk to him about this? We have not visited her yet since then?I know deep inside that he still is concern but is overwhelmed by his anger. How can I help fix bridges. I love the both of them dearly and I do feel for their mom who is saddened by everything. I need help.