Does a divorce issued by the father three times take effect, despite his denial of the third divorce and his claim not to remember it, and his claim that the second divorce did not occur, and is their marriage still valid?

Righteousness towards parents is obligatory and is not negated by their ill-treatment. Disliking in one's heart what emanates from them that is not approved by the Shari'a is not an act of disobedience (ʿuqūq). One must advise a parent gently and kindly, praying for their guidance if they commit grave sins such as lying, stealing, and unlawfully consuming people's wealth. Divorce is a serious matter, and it is not permissible to lie to a judge or a mufti (definition) regarding it. If the mother is certain that the triple divorce has occurred, she must separate from her husband.