How can one disavow a father who was an adulterer, conceived children through adultery, and died in that state, and a mother who was disobedient to her own mother, foolish, invoked evil, concealed disbelief while claiming Islam, especially after being afflicted by them and suffering severe harm in life due to their actions?

If the father's adultery is confirmed, it is a grave sin, but it does not negate the obligation to honor him and treat him kindly, both alive and dead. Supplicating for him with mercy and forgiveness remains. Accusing the mother of disbelief is serious and requires clear proof. If she is disobedient to her mother, it is a great evil, and one must supplicate for her guidance and advise her in the best manner. There is no sin in disliking the mother's bad actions, but one must be careful not to let this lead to mistreating her.