Find a book: A wealthy woman owns a glass factory. She adopts the child of her husband and his lover ...?

when they are killed in a car accident. The woman did not even know her husband was having an affair. The child does not find out she was adopted until she is an adult. The daughter has an intense rivalry with a young woman who worked for her mother but is later fired. The daughter marries an intelligent but poor man who is trying to establish his own electrical business. Her mother does not approve of the marriage.