How And What Could I Do For A Son Who

How and what could I do for a son who is 19 years old and his far ther has stage 4 liver cancer and is on life support and the Doctors have said he will not make it, however the son is left to deal with all of this and feels his father will get better because he is only 43y/o. How can I help the 19 y/o son understand" also he did not inform his son of the cancer. Please help.