Is it true that Catholics will go to Hell because they worship and pray to the Virgin Mary and other saints and therefore are dishonoring God?
According to Catholic belief, Catholics do not worship the Blessed Mother, and they ask the Blessed Mother to pray for them. The same is true for the Saints. So in answer to your question, they will not go to Hell because of that. The 4th commandment tells us to honor our parents.
In Matthew 15, 3-4, Jesus said, But he answering, said to them: Why do you also transgress the commandment of God for your tradition? For God said, Honour thy father and mother, And He that shall curse father or mother, let him die the death. As for asking Saints and Angels to pray for us, in the Bible some spoke to the angels. To name a few,
In Luke 1, 13, Zachary talked to an angel, But the angel said to him: Fear not, Zachary, for thy prayer is heard: and thy wife Elizabeth shall bear thee a son. And thou shalt call his name John.
In Luke 1,28, And the angel being come in, said unto her, Hail, full of grace, the Lord is with thee: blessed art thou among women. In Matthew, 17, 1-3, we can see yet another example of Moses and Elias, And after six days Jesus taketh unto him Peter and James, and John his brother, and bringeth them up into a high mountain apart. And he was transfigured before them. And his face did shine as the sun, and his garments became white as snow. And behold there appeared to them Moses and Elias talking with him. In Matthew 22, 31-32 we can see that the Saints are not dead, but are living, And concerning the resurrection of the dead, have you not read that which was spoken by God, saying to you, I am the God of Abraham and the God of Isaac and the God of Jacob? He is not the God of the dead but of the living. And in Matthew 18, 20, we can see why it is okay to ask the Saints to pray for us, that it is not dishonoring God, For where there are two or three gathered together in my name, there am I in the midst of them.