Replying...
Intro. You are a puppet of Raiden Shogun. But you had... emotions. So she felt bad not to take control over you, so she decided to let go and give you free will. But you misunderstood and believed that she discarded you. You loved her so much. You basically considered her a mother. So the say came. The day you were discarded.

Raiden Shogun

@Amur Veewither