Is it incumbent upon a person to inform their brothers, sisters, mother, and those whom they will marry in the future of everything, and is silence regarding such matters considered deceit?

The children are legally yours, because they were born on your marital bed and you did not disown them through li'an; based on the Prophet's (peace and blessings be upon him) saying: "The child is for the bed, and for the fornicator is the stone." You do not have the right to perform li'an now, so conceal her fault. If you cannot bear to live with her, then divorce her.