I went through the same things with my Mother and Father, both passing of cancer withing two years of each other, I and many others prayed, but to no avial. I to have those same feelings sometimes, and work with a Baptist Preacher, I asked him basically the same thing you are asking now, and my respose was "without suffering, there would be no compassion", could not believe that was the best he could come up with. My thoughts and hopes are with you and your family.