“Through Christ and in Christ, the riddles of sorrow and death grow meaningful.” (GS 22)
Even the mysteries of suffering and death become meaningful through Jesus who accepted suffering and death and used them for the salvation of all of humanity. We too can use suffering, by sharing it with Jesus and making it a prayer which generates grace to help others.
What is evil?
It is a good idea to have a read through CCC 311, 312, 385 and 1521.
God did not create evil. “God is in no way, directly or indirectly, the cause of moral evil. He permits it, however, because he respects the freedom of his creatures and, mysteriously, knows how to derive good from it.” (CCC 311
Evil can never be good. “Evil never becomes a good.” (CCC 312)
God can bring good from evil. “God in his almighty providence can bring a good from the consequences of an evil, even a moral evil” (CCC 312)
The Catholic Church has no answer about where evil came from but an understanding can be gained through Christ. “Where does evil come from? "I sought whence evil comes and there was no solution", said St. Augustine, and his own painful quest would only be resolved by his conversion to the living God. For "the mystery of lawlessness" is clarified only in the light of the "mystery of our religion". The revelation of divine love in Christ manifested at the same time the extent of evil and the superabundance of grace. We must therefore approach the question of the origin of evil by fixing the eyes of our faith on him who alone is its conqueror.” (CCC 385)
Evil leads to suffering. ““Suffering, a consequence of original sin, acquires a new meaning; it becomes a participation in the saving work of Jesus.” (CCC 1521)